Georgette Douwma / Composite image of echinoderms on black background. Species present: - Top row from left: Yellow sea cucumber (Colochirus robustus) and Lampert's sea cucumber (Synaptula lamperti), Black sea c...

David Fleetham / Ten-lined urchin (Eucidaris metularia) nestled on a reef, close up, Hawaii, Pacific Ocean.

Francisco Marquez / Pencil tip hedgehog sea urchin (Eucidaris thouarsii) on white background, Islas Marias Archipelago, Mexico.