not a tuesday nudibranch but a related species albeit one related only in most diver's minds.
Above is a flatworm - they aren't particularly closely related to nudis but being slowmoving (sort of - they can swim after a fashion) sluglike invertebrates they often get lumped together contextually.
This one is Pseudobiceros pardalis and I was absolutely astonished when I found it on Saturday. These are the sorts of critters we see only very rarely here in the Caribbean compared to the more biodiverse indopacific. No-one else on the boat has found one here before so I was delighted to bag some shots of this one.