Arachnocrea scabrida

The fruitbody consists of a small, roughly spherical chamber (technically a perithecium) in which the spore-producing organs are contained. Each perithecium is pale brown and no more than about a quarter of a millimetre in diameter. However, perithecia are likely to occur in abundance, embedded in a communal white to very pale brown sheet, so that the mass of fruitbodies is visible to the naked eye. The sheet is fairly soft (somewhat like compressed cotton wool), with wispy edges and is loosely attached to its woody substrate.    

A sheet with a colony of fruitbodies may cover a square centimetre or two.

The first published description of Arachnocrea scabrida, based on material collected in Japan, appeared in 1972. Since then the species has been found in south China, New Zealand, French Guiana and Australia.

Look-alikes

Arachnocrea stipata is similar. The differences are in the microscopic details,  the major one being that Arachnocrea stipata has smooth spores whereas those of Arachnocrea scabrida have a warty ornamentation. Both species are found in Australia and there is more in the reference  listed below. While a microscope is necessary to identify the species, it should be easy to recognize the genus with the naked eye. Some other genera of fungi produce white or brownish, sheet-like fruitbodies (textures ranging from cotton-wool-like to leathery). Sometimes they exude small droplets (occasionally brownish) and, at first glance, there could be a slight chance of confusion, but a closer look (ideally with the help of a hand lens or a camera’s macro lens) should make it clear that you don’t have an Arachnocrea.  

Reference

Lepp, H. (2018). Arachnocrea, a perithecial ascomycete, Fungimap Newsletter, 58, 20-21.