Their skeletons are prized by beachcombers, but sand dollars look way different in their lives beneath the waves. Covered in thousands of purple spines, they have a bizarre diet that helps them exploit the turbulent waters of the sandy sea floor.
These Caribbean crabs will tear each other limb from limb to get the best burrow.
Planarians are tiny googly-eyed flatworms that can regrow their entire body.
House centipedes are masterful predators with a knack for fancy footwork.
