Langula

Langula is a genus of lingulid brachiopods, one of the oldest known groups of shelled animals. These inarticulate brachiopods are characterized by their long, tongue-shaped shells (hence the name, which derives from the Latin "lingula" meaning "little tongue").

Langula shells are composed of calcium phosphate rather than calcium carbonate, which is more common in most other brachiopods and mollusks. This phosphatic composition is a primitive trait, reflecting the early origins of the genus.

Fossils of Langula and related genera have been found in rocks dating back to the Ordovician period (approximately 485 to 444 million years ago), and the genus persists to the present day, making it a "living fossil". This remarkable longevity indicates that Langula has remained largely unchanged morphologically over vast stretches of geological time.

Langula typically inhabits burrows in shallow marine sediments, where they feed on suspended organic matter. They are found in various parts of the world, including the Indo-Pacific region.

The study of Langula is important for understanding the early evolution of brachiopods, the Cambrian explosion, and the processes of evolutionary stasis (where organisms exhibit little morphological change over long periods).