No interactions present.
you have as Lee said edible periwinkle (Littorina littorea) but also grey topshell (Gibbula cinerea), purple topshell (Gibbula umbilicalis) and finally common limpet (Patella vulgata) - oh and not forgetting your barnacle which looks like (Semibalanus balanoides).
Amazing how tolerant different spp are and what a single crevice can hide.
All of these are invertebrates and I would edit your pic and move to this section :)
Thank you. Will do.
...also post this 5 times for each sp. Leave this one but edit your title to be edible periwinkle and then we can agree with Lee. Put further 4 posts with titles and sp as suggested above and we can agree with you.
Lat/Lng: 50.2897, -3.8943
OS grid ref: SX651450