A new genus and species of mickwitziid-Wimanigma soderarmensis-is described from glacial drift material most probably derived from the Cambrian (Series 2, Stage 4) File Haidar Formation, occurring now as subcrops beneath the Bothnian Sea (the region between Sweden and Finland separating the Bay of Bothnia from the Baltic Sea). The material was previously referred to Mickwitzia Schmidt 1888, also known from glacial drift in the same area. However, Wimanigma clearly differs from the strongly mineralised Mickwitzia in having a less mineralised and softer shell, composed of easily fragmented, roughly triangular units of similar size, with very strong and regularly spaced comarginal corrugations. Each triangular unit has pustulose ornamentation typical of mickwitziids, and the shell is penetrated by vertical pores or tubules. Wimanigma soderarmensis is considered to represent a mickwitziid stem brachiopod.