(I hope you can see the WHOLE image.)
Limpet tracks on the left; periwinkle tracks in the middle. OK? So who left the zig-zag tracks on the right?
No interactions present.
Yes, picture 3 has no reference in Comments but your nearby post http://www.ispotnature.org/node/102297 says it all.
I am here because I am researching for Patella post; but see this http://www.ispotnature.org/node/329880
Lat/Lng: 55.57663, -1.63992
OS grid ref: NU228314
Within 100 metres or so, at different times.