File:A slime mould - Trichia persimilis - geograph.org.uk - 1524494.jpg

English: A slime mould - Trichia persimilis. This was just one of at least five different slime mould species (see 1528103 for the others) that were present, all at the same time, on a particularly productive log, not far from a large artificial mound (1470482). For scale, the orange patch on the left is about 2cm across, from left to right.

These colonies developed from an earlier plasmodial phase; at that stage, the slime mould really is slime (it looked like wallpaper paste). The plasmodium moves over the wood rather like a giant amoeba, ingesting bacteria. It later "fruits", forming the spore-producing structures (sporocarps) shown here; the sporocarps are the individual small rounded structures visible in the photo. What is left over is the so-called hypothallus, visible here as a translucent substance.

[Such densely-packed colonies are quite characteristic of T. persimilis and the similar T. scabra. Two separate fruitings are shown in this image; the one on the right came from a different plasmodium, and is two or three days behind the colony on the left.]

The sporocarps mature from white, through yellow, to the orange colour shown here, darkening further to a brownish colour. Their outer layer (peridium) then disintegrates, exposing a fluffy mass of spirally-bound threads called elaters (for their function, see 1493931).

This species and the closely-related T. affinis are frequently attacked by a parasitic fungus called Polycephalomyces tomentosus [see "The Myxomycetes of Britain and Ireland" by Bruce Ing], causing spiky outgrowths.