A diamondlike structure gives some starfish skeletons their strength

A microscale pattern compensates for the weakness of the calcite mineral

three starfish on the ocean floor

Beneath the skin of knobby starfish is a skeleton made of brittle, stonelike growths that derive strength from an unexpected internal structure.

Ria Tan/Flickr (CC BY-SA 2.0)

Some starfish made of a brittle material fortify themselves with architectural antics.