The Florida Lyonsia, Lyonsia floridana Conrad, 1849, is a relatively common bivalve in the estuaries of Southwest Florida, in particular in areas with dense, compact mud. The half-inch shell is very thin, fragile and translucent. The young attach themselves to broken shells or small pebbles, by a very slender bundle of fibers called byssus. Unlike what happens to sturdier clam shells, the delicate nature of the Florida Lyonsia renders preservation of its shell difficult after the death of the animal. This and the fact that the species is only found in difficult-to-reach, muddy areas make the species hard to collect.
The Florida Lyonsia, Lyonsia floridana; top, internal view of left valve, right, external view of right valve.