Chaetosphaerella phaeostroma

The fruit bodies or perithecia are dark grey to black, almost spherical and part immersed in a dense fuzzy black mat of hyphae. Conidia can be produced by the hyphae.  The perithecia produce ascis with 8 ascospores.  The ascospores are curved and 4-celled, and the middle two cells are brown and the end cells hyaline 

There are several similar species

microscopy

Photograph on the substrate, and note habitat and substrate in your comments.  We recommend this is verified from a specimen by an expert before submission to NatureSpot; microscopic examination may be needed.

They grow crowded together on rotten wood from deciduous trees, including that of Beech, Grey Willow, Sycamore, Field Maple and Ash. (May extend several centimetres along the host.)

Fruiting from autumn to spring.