A flask-shaped cavity in the thallus of some brown algae, e.g. Fucus, in which gametangia are formed. A female conceptacle is lined with unbranched sterile hairs or *paraphysis
, and the *oogonia
develop from short stalks arising from the chamber wall. The male conceptacle is filled with branched hairs that bear antheridia. The conceptacle opens via an osteole.