High on the dry rocks at Fall Bay in Gower I spotted this fine creature running across the surface. It has many common names: sea slater, bilge bug, littoral wood louse, for example, but it’s scientific name is Ligia oceanica Linnaeus. With a body length of up to 25 mm it is the largest north-west European oniscid isopod. I picked it up to have a closer look at the wonderful texture and markings on its hard segmented covering. The books say that it is a frequent inhabitant of crevices in the upper rocky shore above high water mark but I have only seen it myself a couple of times in my lifetime of mooching on seashores.
Hayward, P. J., and Ryland, J. S. (2017) Handbook of the marine fauna of north-west Europe, Second Edition, Oxford University Press, ISBN 978-0-19-954945-0, p 350.