The Acrotretida are a group of sessile, suspension-feeding brachiopods known from the Cambrian period and surviving until the present day. Their shell has a round outline, and is usually phosphatic in recent specimens. ...
Found on
http://en.wikipedia.org/wiki/Acrotretida
(from the article `lamp shells`) ...surface apical, or located at the tip, in both valves; fleshy pedicle emerging between the valves at the tapered end; about 51 genera; Cambrian to ...
Found on
http://www.britannica.com/eb/a-z/a/13
No exact match found.
