Found on rocks on shore above high tide mark. Compare with dead grass and heather for size.
No interactions present.
Definitely Petrobius and probably P. maritimus the common, widespread UK species, but without a specimens and a microscope P. brevistylus maybe can't be ruled out. See http://www.marlin.ac.uk/speciesinformation.php?speciesID=4081
Nick Upton, naturalist and photographer.
Lat/Lng: 49.9841, -5.2442
OS grid ref: SW675143