W. extenuata is a very common weft moss of wet forest. It occupies a variety of substrates including rock, tree bark and logs. The shoots have a characteristic look whereby the tips of the main and side branches end in a sharp point, hence the common name. The leaves are oval to obovate and taper abruptly into a long hairpoint. The alar cell regions the leaf bases are also quite well developed. Capsules are not very common.

W. extenuata is superficially similar to Calliergonella cuspidata but differs in being a bit for wiry looking and having an easily discernable long hairpoint on the leaves.