#arcyria

A slime mold, Arcyria ferruginea, grows on dead wood in Hertfordshire, UK. Despite their common name, slime molds are not fungal, and are in fact an amoeba-like organism that clumps together in large structures.

... 8 hours later:

Arcyria denudata slime mold

I brought home this white slime mold three days ago. I had to figure out how I could transport it home without damaging it, since it was still transitioning out of its plasmodial state and was therefore still very soft, like jello that hasn't set.

After a day, it turned this burnt red color. (Fingernail for scale)

And today, on day 3, I see that it is Arcyria (denudata?). The spore-bearing threads have formed and spores are ready to be released to the wind.