Build a House for Hermit Crab: A Sensory Play Tray

By Adventures and Play TeamPublished: May 22, 2017Updated: May 15, 2026

A House for Hermit Crab by Eric Carle is the picture book where the hermit crab outgrows his shell, finds a new one, and spends a year decorating it with the help of a parade of sea creatures. Sea anemones, starfish, coral, snails, sea urchins. Each new friend brings something the crab uses to make the place feel like home. The book ends with him outgrowing that shell too, leaving it well decorated for the next hermit crab to move in.

The activity was an extension of the book. Build a small “sea floor” on a tray of tinted water, set out a coconut-shell “shell” for the kid to decorate, and let them play out the book’s idea: small creatures help a crab make a house. A picture-book activity with a real craft built into the play.

This one was tested in two versions before we settled on what worked. The wet version (water in the tray) looked the best in photos but the mounting putty didn’t grip wet surfaces. The dry version (no water, no gravel) was the practical winner.

Build a House for Hermit Crab Pinterest pin. Overhead view of a shallow sand-colored tray filled with shallow blue-tinted water, scattered with seashells, plastic starfish, gold coins, aquarium plants, and gemstones. Two small plastic hermit crabs sit at the front edge. A halved coconut shell with sea creatures stuck to its outside sits in the middle as a hermit crab's decorated house.

Painting the tray sand-colored

The starting point was a black plastic play tray of the sort sold in the UK for children’s sensory play. They come in black, blue, or red as standard. Blue is the easiest to find in the US. None of the standard colors looked enough like a sea floor.

The fix was to spray-paint the inside of the tray with a textured outdoor paint in a sand-or-stone color. The textured paint is forgiving: a heavy hand and a poor angle still produce something that looks like rough beach sand rather than uneven spray. One can covered one tray with paint to spare.

A black plastic shallow play tray laid on a paved outdoor surface, half-painted with a sand-colored textured spray paint. The painted half shows a stippled tan and beige finish that looks like fine sand or rough stone. The unpainted half shows the original black plastic. A can of textured outdoor spray paint sits next to the tray.

Let it dry overnight before water touches it. Two hours is not enough; the paint stays slightly tacky and the first time a wet sponge wipes it the color lifts.

Sea floor inventory

What ended up on the tray:

  • Two small plastic hermit crab figures, the size of a walnut
  • Four halves of dried coconut shell, the kind sold in pet stores as reptile hiding caves. These are the “houses” for the crabs to decorate.
  • A small pile of real seashells in mixed sizes
  • Plastic starfish in assorted colors
  • Mixed plastic sea-life figures (a small octopus, a couple of fish, a seahorse)
  • A handful of gold plastic coins, the kind sold for treasure-hunt party games
  • Aquarium plants, the silk or plastic kind sold for fish tanks
  • Acrylic gemstones in glass-bead size, the kind sold for vase fillers
  • Aquarium gravel in fine grain (we eventually took this back out)
  • Reusable mounting putty in small balls, one ball per kid
  • Water with a couple of drops of blue food coloring (optional)

Most of the items live in our craft drawer between activities and reappear elsewhere. The coconut-shell halves came from a pet store, sold as small-reptile caves; the same brand sells them as bird-cage hideaways too.

The sand-colored tray viewed from above. A shallow layer of fine aquarium gravel covers part of the base, with shallow blue-tinted water pooled across the rest. Plastic starfish, seashells, an octopus figure, gold coins, gemstones, and small aquarium plants are scattered across the surface. Two plastic hermit crabs are tucked among the items.

Decorating a coconut-shell house

The setup is the prep; the play is the decorating. The kid picks one coconut-shell half as their hermit crab’s house, then chooses creatures and treasures from the tray to “stick” onto the outside using small pieces of reusable mounting putty. A small starfish on the side, a seashell on the top, two gemstones for eyes, an aquarium plant trailing off the back. The crab climbs into the inside of the shell. The kid moves the whole assembly around the tray.

The picture-book tie-in is the part that holds the activity together. After the first round of decorating, we read the relevant page from Eric Carle’s book (“the hermit crab met a starfish and asked it to decorate his shell”), then the kid added that creature to their own house and moved on. By the end the kid had a coconut shell with seven or eight sea-life items stuck on the outside, the same pattern as the book.

For another picture-book activity with a sensory bin and small sea-or-snow creatures stuck across a base, see our Penguin Story Stones, where painted-pebble penguins live among marshmallows in a tinted bin instead.

A close-up of a halved coconut shell standing on its open end on the painted sand tray. A plastic hermit crab is climbing into the shell's hollow interior. Two small starfish, a yellow seashell, and a green sea plant are stuck to the outside of the coconut shell with small dabs of mounting putty visible at the join points.

Two coconut-shell hermit crab houses side by side on the painted tray. Both are decorated with a different combination of seashells, starfish, gemstones and small aquarium plants stuck to their outsides. A child's hand is in the frame, placing one more gemstone onto the front of the right-hand house.

What did not stick

Two things did not work on the first pass.

The gravel made the tray look too busy in photographs. With seashells, gemstones, plants, plastic coins, and gravel all on the same plane, the eye could not find the hermit crab or the coconut house easily. Without the gravel, the painted tray was its own visual texture and the items stood out cleanly. We took the gravel back out the second time.

The mounting putty also did not stick well to wet coconut shells. We had tested the putty dry, and it gripped fine. Once the shell sat in water for a couple of minutes the outside got slick and items slid off after a few seconds. The fix was either to skip the water entirely or to give kids the dry-shell version: water in the tray, hermit crabs in the water, coconut shells set out separately on the dry rim of the tray with putty.

The dry version of the activity, no water in the tray. The sand-painted tray is now an open beach floor with hermit crabs, coconut-shell houses, seashells, starfish and plants scattered across it. Without water and gravel the layout is more readable and each piece visibly stands on the textured paint.

A wider view of the dry version with both kids playing across the tray. Two coconut-shell houses, both decorated, sit in the center. Plastic hermit crabs are tucked among seashells and starfish. A small atlas of sea-life pictures is visible at the edge of the frame for reference.

The dry version kept the same play pattern as the wet one, with two practical wins: the putty gripped, and the photographs were less cluttered. The kids did not seem to care which version they were playing. They picked up the hermit crabs, picked up the shells, and started decorating either way.

For paper versions of the sea creatures the kid spent the activity placing and rearranging, our animal coloring pages cover crabs, fish, octopi, starfish, and the rest of the sea-creature cast.

Final overhead Pinterest-style photo. The decorated coconut hermit-crab houses sit prominently in the center of the painted sand tray, surrounded by scattered shells, starfish, plastic plants, and the two hermit crabs themselves. A small copy of A House for Hermit Crab by Eric Carle is propped against one edge of the tray for reference.

The tray went back into the cupboard at the end of the week. The decorations came off the coconut shells (the putty peeled cleanly), the gemstones and plants went back into the craft drawer, and the hermit-crab figures got rinsed and stored in a small box. The painted tray is the only thing that stayed dedicated. Next time we use it, it will be ready for the next book whose pages happen to fit on a sand floor.

About The Author

Our team of illustrators, writers, designers, and editors works together to craft original, family-friendly coloring pages, printable activities, and simple creative tools for home, classroom, and library use. Each page is thoughtfully created, then reviewed for clarity, accessibility, and quality before it goes live. Adventures and Play has been a small creative corner of the internet since 2017, and since taking over the site in 2025 our team has grown it into a free library of printable coloring pages, an online coloring tool, and a printable maze generator — alongside a careful refresh of the original blog archive of crafts, sensory play, and learning ideas. We're dedicated to making creativity accessible for children, parents, and teachers, with new designs and ideas shaped by what visitors actually use. Learn more about our story and the team on our About page. You can reach us directly via our Contact page or connect with us on our social channels.