|Good morning Ivan,
As far as I can tell, the colour of the dorsal surfaces depends on the species and the age of the limpet. The dorsal aspect of the yellow Patella rustica tends to be much darker (dark blue/brown) than that of Patella vulgata which looks chalky grey on the rocks. Also the larger, and therefore older limpets, are very faded in comparison. Another reason for the apparent drabness of the dorsal surface is the presence of barnacles and encrusting grey alagae on the surface, particularly on the older limpets, thus rendering the whole colony a uniform grey.
The colour of the ventral surfaces of these limpets looked much more saturated than normal because of the fine Norwegian drizzle, which worked to my advantage. I should have added that to my note.
I shall be offline for about 7 days, so I won't be visiting anyone. Please accept my apologies in advance.
I hope you both have a good weekend.
Warm wishes, Amelia
Variation in Limpets (32) *