Lingula

Lingula anatina is a brachiopod that lives in vertical burrows in intertidal sand and mud in the Indo-Pacific. Shells that look almost identical are found in rocks about half a billion years old, which has made the genus Lingula a standard example of a "living fossil".

🧬 Field Guide Specimen: Open Lingula Lamp Shell in the CRV Science Field Guide to log the specimen, see its place among the Lophotrochozoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

Unlike the calcite shells of many brachiopods and most molluscs, the valves of Lingula are made of chitin and calcium phosphate. A long, muscular stalk (pedicle) anchors the animal and lets it retract deep into the burrow when disturbed.

The overall form of lingulid shells has changed little since the Cambrian or Ordovician, but the lineage has certainly continued to evolve at the molecular level. The apparent stasis may reflect a stable burrowing lifestyle in shallow seas. See Transverse Lamp Shell.

Lingula is eaten in parts of East Asia. It survived mass extinctions that eliminated most brachiopods, and its tolerance of low-oxygen mud may have helped.

• Transverse Lamp Shell — a calcite-shelled brachiopod
• Neopilina — another living fossil