Collemopsidium ostrearum (Vain.) F. Mohr
Thallus submerged in the substrate and not very visible except sometimes in the form of a very fine network on the surface of the substrate. Perithecia sessile or slightly buried in a small cavity in the substratum, roughly conical and somewhat angular with a more or less flattened and irregular apex, 0.3-0.6 mm in diameter at the base; very important involucrellum often spreading widely on the substrate by including fragments of this substrate and sometimes several perithecia, the perithecia are sometimes and then typically arranged in clusters in the form of small pearl necklaces. Spores broadly elliptical and club-shaped, colorless, 1-septate, 23-25 â€‹â€‹x 9-11 µm. Pycnidia abundant, smaller than the peritheces, black. Species of the foreshore coming on the shells and more rarely on the limestone rocks. For the moment this species is only known with certainty from Sao Tomé and Principé and New Zealand, the European specimen are doubtful and those which have been sequenced have not been confirmed by this technique.