''Tortula acaulon'', formerly '' Phascum cuspidatum'', the cuspidate earth-moss or toothed phascum moss, is a

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...

with 3 mm leaves which forms green patches. It is very common and has a number of varieties in a wide range of habitats. The variety ''piliferum'' occurs on sandy soils near the sea.'' Tortula acaulon ''
BBS Field guide

References

Flora of the United Kingdom Pottiaceae {{Bryophyte-stub