Steppe mouse-moss or coscinodon moss (Coscinodon calyptratus) is a widespread and common moss on rocks in dry open grasslands in the Kamloops area as well as dry hot habitats in the Southern Interior. It is absent on the coast and in the Rockies to the east.

It forms dense round cushions on rocks.

The narrow leaves form long silvery shiny hair tips that likely help to reflect some of the intense solar radiation. The leaves have a single, long midrib.

The short square leaf cells are one-cell thick. 

The leaf cells near the leaf base are larger and less green than cells near the middle of the leaf.

The most distinctive feature of steppe mouse-moss are the numerous capsules that are often present. The capsule is frequently covered in large papery covering called a calyptra (hence the species name). The large papery covering helps to distinguish steppe mouse-moss from many other similar species of moss that also frequently occur in dry, hot, open habitats on rocks. Many of these species are in the genus Grimmia but these species have much smaller paper coverings unlike those of steppe mouse-moss.

Sometimes capsules and their large papery coverings are absent which then makes it difficult to accurately identify steppe-mouse moss in the field.