Acrotretida
Quick Summary
The Acrotretida are an order of extinct brachiopods, commonly known as lamp shells. These marine invertebrates are characterized by their small, fossilized shells, which are frequently found in Cambrian rocks. The Acrotretida typically have a circular outline and a shell composed of either phosphate or punctate calcareous material. A distinctive feature is that the opening for the pedicle, a stalk-like organ used for attachment, is confined to the ventral valve. This order first appeared in the early Cambrian period and persisted through the Holocene epoch.12
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