Growing on a decaying silver birch, in a deciduous wood, semi-shaded. Nearby Birch Polypore and Blushing Bracket found. Area of lichen coverage approx. 150mm x 60mm.
This would have been one to revisit after a few days because I think it would have turned out to be a myxomycete. Probably Fuligo septica, but I leave these to other people.