There are many zoo hitch hikers that are not good. If its the same or similar color of the zoos, keep it in a nano and see if it will eat
a zoo polyp that is colored similar to it. Its hard to tell from the pictures but it looks like it has a double spiked tail and
those kind eat zoos and if thats the case, there are so many nudibranch species to go through its hard to tell what family and
genus its in without going through a lot of research.