What is "tentaculites"

n. (plural of tentaculite English)

Tentaculites is an extinct genus of conical fossils of uncertain affinity, known from Lower Ordovician to Upper Devonian deposits both as calcitic shells with a brachiopod-like microstructure and carbonaceous 'linings'. The "tentaculites" (i.e. tentaculita) are also referred to as the styliolinids.