Slime Mould Mucilago crustacea
I have seen this species only about three times but that is probably because it lives on grass and I do most of my searching in woodland, which has numerous species.
These two colonies were at the top of a chalk hill in a field grazed by sheep.
Olympus EM-1, (aperture priority), Olympus 4/3 50mm f2 macro, 1/125 at f11 ISO 1600, hand-held.
The stereos are crosseye.