Mimetaster

Mimetaster is a Devonian marrellomorph known from the Lower Devonian Hunsrück Slate, and is the most common arthropod (trilobites excluded) from the locality, known from over 100 specimens including three juveniles. The animals probably lived in small groups.
"Mimetaster florestaensis" is characterized by three pairs of principal spines, as well as strong secondary spines in the proximal two-thirds of the anterolateral spines. It was found in the Tremadocian Floresta Formation of Argentina, the first occurrence of this group in South America.