I think it's Arcyria- happy to be corrected. Grew this out of a scrap of bark in a jar on my windowsill — wood collected from Queen's Wood, Highgate.
These pinkish-red blobs are the fruiting bodies of a slime mould. For most of its life it's a single crawling cell with no fixed shape; then it stops, and does this. What you're looking at is the still phase of something that was, days ago, slowly moving.












