''Arenicolites'' is a U-shaped ichnotaxon (trace fossil) dating from

Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and th ...

times onwards in South Australia. The trace shown by this fossil, is a pair of closely spaced circles on a

bedding plane In geology, a bed is a layer of sediment, sedimentary rock, or pyroclastic material "bounded above and below by more or less well-defined bedding surfaces".Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2005. ''Glossary of Geology'' ...

. In vertical section the traces are U or J shaped. They appear to be burrows made by a kind of worm.

References

Trace fossils Ediacaran life {{trace-fossil-stub