I am not sure if this sea slug, clown nudibranch Ceratosoma amoenum, is common. Last summer we saw many of them on the rocks in very shallow water, perhaps less than one meter deep, in Maitai Bay in Northland. However, I don’t remember seeing them there in previous years. I used to see them regularly in Mahurangi Harbour crawling on silty bottom, but that was a couple of years ago. I still meet them regularly in Matheson Bay in Leigh, most of the time in the channel between the islet and the shore. Hmm, I should mention the city beach of Browns Bay in Auckland, I saw the slugs there as well. That place is good for nudibranches in general I think, especially in early spring when they mate and can be seen everywhere. So back to my question, is clown nudibranch a common slug or not?