Crassula grisea is a small, erect, branched shrublet reaching about 20 cm in height.
It produces many tiny, opposite, cylindrical leaves with rounded or pointed tips and tapering bases. The decussate arrangement of leaves on the densely leaved and brittle stems may be more or less regular and pronounced on different plants. Leaf colour may be bright yellow with a faint greenish tinge as in the picture provided, but leaves may also be pale grey, blue-grey or greenish. There may either be a finely velvety or a glabrous surface on the leaves. Old leaves tend to persist.
Each inflorescence, growing on a single hairy stalk that emerges from a stem-top, consists of a dense cluster, a round-topped thyrse of small flowers. There may be several on one plant.
The fleshy and hairy sepals have pointed tips, appearing dominant over the petals. The tiny, cream petals form a tubular corolla that fades to brown. The protruding anthers are brown. Blooming occurs in winter, the rainy season.
The species distribution is in the far northwest of the Northern Cape, the Richtersveld, as well as in Namibia across the Gariep.
The habitat is arid scrub veld. The species is not considered threatened in habitat early in the twenty first century (Frandsen, 2017; JSTOR; http://crassulaceae.net; http://redlist.sanbi.org).