These are my local rock pools at the Trefusis headland near Flushing. On the right is Penryn River (which is not a river at all) with Falmouth on the other bank. Further to the right around Falmouth is the open sea. To the left the Fal Estuary (or Carrick Roads) going all the way to Truro, the capital of Cornwall.
The seaweed composition had again changed since I last visited. This time there was one red weed dominating the pools, I believe it is the Pacific invader Devil’s tongue weed Grateloupia turuturu (which appeared in my aquarium at some point as well):
The most common sea slug (nudibranch) here is the Sea lemon Archidorus pseudoargus: