How to recognize Gymnostomum aeruginosum: This little moss forms tufts with leaves spread wide when wet, and appressed and contorted when dry. The leaves are 0.6 to 1 mm long, ligulate to linear-lanceolate. The single costa ends just below the apex. Under the microscope leaf cross sections show multipapillose cells on both surfaces and two stereid bands in the costa, although the one on the back of the leaf is often weak or absent. Sometimes the leaf is bistratose. Cross sections of the stem show a central strand usually present. Hymenostylium recurvirostre can be confused with this species, but it has no central strand, and recurved lower leaf margins.
Where to find Gymnostomum aeruginosum: Look on thin soil, and rock crevices.