I started a Cornish shell collection with my children recently. So yesterday we went to our local beach on Flushing to look for new additions. Lying down I took a really close look and was rewarded with a whole bunch of tiny species. On this photo, 14 species comfortably fit on a square inch. Species names in a clockwise spiral:
Bela powisiana
Tritia incrassata (Thick-lipped Dog Whelk)
Trivia arctica (Arctic Cowrie)
Tricolia pullus (Pheasant Shell)
Bittium reticulatum (Needle Whelk)
Littorina obtusata (Flat Periwinkle)
Calliostoma zizyphinum (Painted Top Shell)
Steromphola cineraria (Grey Top Shell)
Littorina saxatilis (Rough Periwinkle)
Tectura virginea (White Tortoise Shell Limpet)
Rissoa lilacina
Peringia ulvae (Mudsnail)
Nucella lapillus (Dog Whelk)
Steromphola umbilicalis (Flat Top Shell)
An Bollenessor 
Just to say, love it all, for the sheer beauty of the seaweeds, especially now I can’t get to the shore to try and view algae underwater to follow your example. As with the algae there are a few of the shells I have not yet found either, just get down to it seems to be the answer. More please.
Thanks Paula!
These shells are all really tiny, so you need to take a very close look! The seaweeds are not at their prettiest in summer usually (better again in October) but there is always something to spot in the rockpools, cheers Mick