Yuknessia
Yuknessia is an early pterobranch, known from the Burgess shale, the Chengjiang and the Wheeler shale. Long, unbranched fronds emerge from a central holdfast-like body covered in small conical plates. The genus contains two species: the type species Y. simplex and Y. stephenensis. It was originally interpreted as a green alga, and has since been reinterpreted it as a colonial pterobranch.
