Vermicularia
The Worm Snail is not a worm but a gastropod (meaning stomach foot) with a worm shaped shell. There are three species in Florida: The Variable Worm Snail, whose shells are fused into what looks like a porous rock (not shown), and the Fargo and Florida Worm Snails. These snails start making their shells by developing a tight spiral. Then after growing to ½” to 1”, (depending on the species) the coil shape begins to straighten out and grow into a long wormlike shape.
Unlike most other gastropods, Worm Snails are sessile, meaning they cement themselves to a solid object and stay fixed there for life. To feed, they shoot out strings of mucus from the mantle, a foot-like appendage at the tube’s opening. These strings stream out into the current forming a sticky web. Plankton and other debris stick to the mucus. The snail then uses its mouth to pull the web back in. As it does, it strains out food through barbs on its tongue (radulae) and devours the catch.
Live shells should never be taken from any Florida State Park.