When a Sally Lightfoot crabs grows too big for its shell, it molts and grows a new one. The foam you can see in this picture is a secretion that helps loosen the old shell.
Once it’s free, the soft crab opens the top of its shell like a hinged lid, and crawls out to start growing a new one. Many discarded shells of these colorful crustaceans litter the beaches of the Galápagos Islands.
Stock Image #20200302-07181826