Physarum cinereum

Usually on decaying leaves or forest floor debris, with sessile sporocarps, globose to ovoid sporothecae 0.3 to 0.5 mm in diameter, white to greyish, with a rough peridium covered with calcium crystals, irregular dehiscence, and black spore mass.

Peridium single, formed by hyaline calcium deposits.

Capillitium abundant, formed by slender hyaline filaments with angular calcareous nodules; columella absent.

Spores globose to ovoid, pale violaceous brown under the microscope, 10 to 12 µm long, 9.5 to 11.5 µm wide, delicately verrucose, ornamented with fine, darker warts.