Mine is just a particularly pretty, but quite abnormally colored, red abalone (Haliotis rufescens) that I found while tidepooling once. With guest appearances by purple urchins (Strongylocentrotus purpuratus) and some acorn barnacles (Balanus sp.)
Abalone are always a treat to see. Some species are pretty endangered along many parts of the US west coast nowadays. They used to be gathered commercially for their meat and shells, but they reproduce slowly and got overfished, so now abalone fisheries are either closed or heavily managed and restricted. They're really fun critters who love to eat seaweed. Sort of like very large, flat snails, but I've worked with them a fair bit and they have a surprising amount of personality.