Keyhole Urchin - Mellita quinquiesperforata -,Florida Maritime Museum - From the FMM Collection: Keyhole Urchin (Sand Dollar) Sand dollars are the dried skeletons (called “tests”) of flat, burrowing sea urchins. This specimen is of the genus Mellita,Keyhole Urchin Photos, Images and Pictures,The Keyhole Urchin, Sand Dollar, Fish Found Commonly Florida's Coast, Vintage PC | eBay,Florida Keyhole Sand Dollar Shells Mellita Quinquiesperforata (10 sand dollars approx. 1+ inches) Sand dollars for crafts décor & display!