Came across this myxo on an oak leaf today and wondered whether identification (at least to genus) might be possible?
Surface was powdery / granular, stipe absent, spore diameter 10 µm.
Externally it looked similar to Mike’s image of Badhamia macrocarpa but I’m totally ignorant when it comes to slime moulds!

[attachment=2]z myxo 190321 014.jpg[/attachment]

[attachment=1]z myxo 190321 017b.jpg[/attachment]

[attachment=0]z myxo 190321-3 10 diam.jpg[/attachment]