On the top edge of bark on a stump, 20 mm humps, hard and dry to the touch. Fuligo septica. Brown buttons in the centre of each hump are the marks left by mutation excluding a drop of water as the humps dry. Overnight the humps become brown and a covering erodes. (See below in the comment.)
The cream coloured roughly textured piles of yesterday afternoon have this morning shrunk slightly and flattened to a velvety brown texture as spores form.
An off-white three cm mound, firm but soft to the touch, covered in a thick layer of very fine brown spores which coat anything that touches them. Appeared over 24 hours: image late afternoon on a fine day after a night of continuous warm rain. Identified as actively shedding slime mould.
I read that DNA analysis indicates that slime moulds of this general type that includes Fuligo septica have been land organisms akin to amoeba for something like a thousand million years, making them perhaps the most durable extant land based life form with a longer history than even the Collembola with survival through every mass extinction over that time. These slimes, that over most of their lives have a single-celled amoeba like existence, have worldwide distribution and thrive in urban areas. They are classed by gardeners as impossible to get rid of and are not on anyone's endangered list.
Five cm field of view. On decaying chip board after rain overnight. Largely disappeared the next day with just strands left.
Fuligo septica. Feels dry like peanut brittle. Appeared suddenly overnight during heavy rain around cracks in the pavement and disappeared over 36 hours.
The description in Wikipedia matches perfectly with this slightly sad example from Bangkok. "Worldwide distribution: often being found on bark mulch in urban areas after heavy rain."