Phylum: Chlorophyta Family: Goniochloridaceae
Pseudostaurastrum enorme (Ralfs) Chodat
Probably common in acidic moorland lochs and pools. 'Irregularly tetrahedral or polyhedral, with a stout central body and short thick bifurcating arms ending in 5-10 µm long spines; ...' - John et al. (2011)
References:
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition) The Freshwater Algal Flora of the British Isles