semiovatus, also known as Panaeolus semiovatus and Anellaria separata, and commonly known as the shiny mottlegill, ringed panaeolus, common fungus of the feces variety,[1] or egghead mottlegill, is a medium-sized buff-colored mushroom that grows on horse dung, and has black spores.

Though nonpoisonous,[2] it is generally regarded as inedible and possessing a rather abysmal taste,[3] and a few people experience gastric upset after consumption.

The cap is up to 8 cm across, dark buff to white, parabolic to nearly convex in maturity.

The stem is 15 cm by 20 mm, solid and smooth, with an annulus (ring) that is white, but is often found blackened by falling spores.

The gills are adnexed, being wider in the middle, and narrowing at both ends, they are brown to black.