Petaloconchus varians (d'Orbigny, 1839) - "worm snails", modern (latest Holocene)

The gastropods (snails & slugs) are a group of molluscs that occupy marine, freshwater, and terrestrial environments. Most gastropods have a calcareous external shell (the snails). Some lack a shell completely, or have reduced internal shells (the slugs & sea slugs & pteropods). Most members of the Gastropoda are marine. Most marine snails are herbivores (algae grazers) or predators/carnivores.

The unusual, squiggly masses seen here are compact colonies of vermetid snail shells. Vermetids are nicknamed "worm shells" or "worm snails" because their shells are highly irregular in shape. Vermetids are filter-feeding, hard-substrate encrusters. They often encrust their shells together into small, reef-like structures.

Classification: Animalia, Mollusca, Gastropoda, Vermetidae

Locality: Lighthouse Point beach, southern shore of the eastern tip of Sanibel Island, Gulf of Mexico coast of southern Florida, USA

See info. at: <a href="https://en.wikipedia.org/wiki/Petaloconchus" rel="noreferrer nofollow">en.wikipedia.org/wiki/Petaloconchus</a> and