''Mobergella'' is a millimetric

Lower Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (m ...

shelly fossil of unknown affinity, usually preserved in phosphate and particularly well known from Swedish strata, where it is diagnostic of lowermost Cambrian rocks. Originally interpreted as a

monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell inhabiting deep sea environments . Extant representatives were not recognized as such until 1952; previously they were known only from ...

n, the circular, cap-shaped shell resembles a

hyolith Hyoliths are animals with small conical surface, conical animal shell, shells, known as fossils from the Palaeozoic era. They are at least considered as lophotrochozoan, and possibly being lophophorates, a group which includes the brachiopods, w ...

operculum, with concentric rings on its upper surface, and seven pairs of internal muscle scars. It is never found in association with a conch, and its affinity therefore remains undetermined. Nevertheless, its heavy musculature does seem to indicate that it functioned as an operculum. Some specimens bear evidence of healed injuries. It's also been compared to the Kirengellids, which are probably brachiopods.Dzik, J. 2010: Brachiopod identity of the alleged monoplacophoran ancestors of cephalopods. Malacologia 52:97–113.

Occurrence

The genus is unique to Lower Cambrian strata and has been found throughout the northern hemisphere.

References

Enigmatic prehistoric animal genera Cambrian animals of Europe Cambrian animals of Asia {{cambrian-animal-stub Cambrian genus extinctions