Circothecidae are a family of Cambrian problematica, sometimes attributed to the Hyolitha,Brasier, M. D. (1986). The succession of small shelly fossils (especially conoidal microfossils) from English Precambrian–Cambrian boundary beds. Geological Magazine, 123(3), 237–256. doi:10.1017/S0016756800034737 though some authors suggest (on the basis of no specified evidence) that they are definitely not.Webers, G. F., & Yochelson, E. L. (1989). Late Cambrian molluscan faunas and the origin of the Cephalopoda. Geological Society, London, Special Publications, 47(1), 29–42. doi:10.1144/gsl.sp.1989.047.01.04
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