Cambrorhytium
Cambrorhytium is an enigmatic fossil genus known from the Latham Shale (California), and the Chengjiang (China) and Burgess Shale (Canadian rockies) lagerstätte. The fossil is conical, with iterated linear markings on its walls, parallel to its base. Its wall is thin, and it lacks the keel that is distinctive of hyoliths. It has been interpreted as a cnidarian polyp, with the interpretation suggesting that the animal lived in the tube and extended tentacles (of which no trace has been found) from the flat aperture. The other possible, but probably unlikely, affinity is with the hyolith molluscs. Its name is  from the Latin "rhytium", drinking horn. "C. elongatum" has been described to contain an alimentary canal in a single Chinese specimen. "C. major" was originally described as a member of the hyolith genus "Orthotheca". "C. fragilis" was originally included by Charles D. Walcott in the genus "Selkirkia", – a taxonomy that was retained by later workers until finally questioned and redescribed as "Cambrorhytium" in the eighties. Its similarity with the lower cambrian species "Torellelloides giganteum" may indicate a close relationship. See also. "Cambrorhytium" has been compared to the fossil "Archotuba" and "Sphenothallus"