I spend plenty of time peering into rock pools around the coast of Jeju. With so much rocky shoreline teeming with little creatures, there’s always something to watch.
I saw these two just outside the harbour at Museulpo this afternoon. There are any number of crabs, like the one below, of different sizes and colours, but I’ve never seen anything like the slug in the photo above. Everything else does its best to blend in with the background, but this fellow doesn’t seem to feel the need. Given that it travels at the speed of a slug, perhaps it relies on being poisonous as a means of defence.
It could be a chromodoris aureopurpurea. There are references on the internet to this species on the coasts of countries around the western Pacific.