Shell Swap: Hermit Crabs app icon

Shell SwapHermit Crabs

Drop a shell, start the chain!

When a hermit crab finds a new shell, a whole line of crabs trades up: the biggest moves in, its old shell goes to the next one, and so on. Scientists call it a vacancy chain. Here, you start it! Drop an empty shell on the sand, watch the crabs line up by size and swap homes one by one, and make every crab happy before the tide comes in.

120 levels 8 shores Daily Tide Free to play
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Drop, Swap, Smile

Inspired by the real vacancy chains of hermit crabs: every level is a cute, clever puzzle about who fits which shell.

START THE CHAIN

  • Drag an empty shell on the sand and drop it somewhere; nearby crabs rush over.
  • They line up by size, biggest first, and each crab moves in if the shell is better than its own.

FIT THE SHELLS

  • A crab is happy in a shell of its own size or one size bigger.
  • Tight, loose or far too big shells make it unhappy, so plan who gets which shell.

BEAT THE TIDE

  • Make every crab happy before your moves run out and the tide comes in.
  • A glowing ring shows who will come while you drag.

3 STARS

  • The fewer the moves, the more the stars.
  • Start a huge chain with one smart move to collect 3 stars.

Why Shell Swap?

A cheerful 3D puzzle with real science at its heart: sunny beaches, cute crabs, sparkling water and a sweet note that climbs with every shell swap.

8 SHORES

  • Calm Cove, Rocky Shore, Gull Beach, Octopus Cave, Coral Reef, Storm Beach, Litter Beach and Royal Lagoon.
  • Rolling rocks, snatching gulls, a trading octopus, picky crabs, storm waves, litter to clean and the giant Crab King.

CRAB WORKSHOP

  • Long Tide, Shell Detector, Quick Sand, Pearl Diver, Sand Wall and Extra Move.
  • Unlock 8 crab colors, one for every new shore.

BEACH FRIENDS

  • The Crab Oracle shows the first move, the Gull Guard dog chases gulls away, the Pelican carries your first shell and the Sea Turtle holds back the tide.

DAILY TIDE

  • A brand-new tide pool every day, with gems for your first finish.

A hint when you're stuck

The Hint shows the next correct move, and if the tide comes in, you can continue with a few more moves. An internet connection is required to play.

Free to play

Shell Swap: Hermit Crabs is free; it contains optional ads and in-app purchases.

Screenshots

A calm cove, rocky shores, a gull on the hunt, an octopus trading shells, a colorful reef, a storm wave, a litter-covered beach and the Crab King's royal lagoon.

Shell Swap – Hermit crabs swapping shells in a chain Shell Swap – Rolling rocks on the rocky shore Shell Swap – A gull diving for an empty shell Shell Swap – The octopus trading a hidden shell Shell Swap – A storm wave sweeping the shore Shell Swap – The Crab King and a happy crowd of crabs

Start the shell chain!

Shell Swap: Hermit Crabs is free. Download it now, drop a shell and make every crab happy.

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