Liocarcinus marmoreus
Liocarcinus marmoreus, sometimes known as the marbled swimming crab, is a species of crab found in the northern Atlantic Ocean and North Sea. It may be found on sand and gravel in the sublittoral and lower littoral zones, down to a depth of , from the Azores and the Alboran Sea (the westernmost section of the Mediterranean Sea) as far north as the Shetland Islands. It reaches a carapace length of , and is distinguished from other similar species by the presence of three similarly sized teeth on the edge of the carapace, between the eyes, and by the marbled colouration on the carapace. L. marmoreus is sometimes parasitised by the barnacle Sacculina. References

Portunoidea
Crustaceans of the Atlantic Ocean
Crustaceans described in 1814