Rhizocorallium

A non-branching, horizontal to slightly inclined, U-shaped trace with a peripheral tunnel and concave laminations called spreite between the tunnels. It is more or less a horizontal version of a vertical U-shaped trace with spreite known as Diplocraterion. Rhizocorallium is generally found in shallow-marine rocks, and it has been suggested that it is a combination feeding trace/dwelling burrow of an annelid worm, or possibly even some sort of arthropod, such as a burrowing shrimp. When Ophiomorpha and Thalassinoides burrows contain meniscate backfilling, they can be confused with Rhizocorallium.