About 2cm long
No interactions present.
I think you have the correct species due to the three 'teeth' at the back end. I think the scientific name is spelt Idotea baltica.
Actually Idotea balthica is correct - I.baltica is a common misspelling.
Origin 3 Feb
I didn't say (originally) EXCELLENT pictures.
My new ID is NOT meant to subvert the correct one. But it is the only way to see the ID panel correctly formed.
PS...Actually though if a few do agree, to the new one, then Other Obs would be seen, this would appear in other Obs (a precious thing) and the Taxonomy links would complete too.
Lat/Lng: 53.8103, -3.0569
OS grid ref: SD305354