#grimmiaceae

Growing on laterite boulders at Mt. Matilda, but very common on rocks in temperate areas worldwide. Such as below, on Sullivan's Rock near Perth, and on a much smaller granite outcrop near Tumbarumba.

There are at least 800 described Grimmia sp., but they're so difficult to ID that herbarium collections worldwide are plagued by misidentifications. The American bryologist Geneva Sayre, who worked on the North American Grimmias, wrote that the genus "contains an ambigua, a varia, a decipiens, a controversa, a revisa and at least two anomalas".

A grey moss that turns green if wet. It covers much of the ground in the Rangipo Desert. Higher up the volcanoes it's even more common.

I'm hardly the first person to notice - this field trip report from 1986, for example

Above about 1350m Racomitrium lanuginosum became a conspicuous part of the vegetation unable to be completely ignored even by 'higher' botanists.

I'm not sure it's lanuginosum though - some resources say that that's a Northern hemisphere species, common in alpine and tundra habitats on acidic boulder scree and bare rock. Which would fit here too. It's also known as woolly fringemoss, hoary rock-moss and woolly moss. 'lanuginosum' means 'with woolly down'. See also Lanugo - soft woolly hair that covers the fetus of some mammals including humans.