It’s called a bunny slug representing a bunny and they eat toxic sponges
There’s no predator that will eat them as they apparently taste bad to fish
They will eventually starve and vanish
It does look like a nudibranch, especially with the black rhinophores, but I am not sure which type it is. Most Dorid nudibranchs have gill frills on the back end in addtion to the rhinophores. Elysia nudibranchs look similar to what you show, except they typically have a much more frilly skirt around the perimeter and on the back. It seems like some type of Elysia nudibranch, but I have not seen one like this before nor can I find it with an online search so far.
Thanks everybody. This is out of the tank as I don't want to take any chances but it would be interesting to know what exactly it is. I don't think it's a bunny slug as it doesn't have the tail and it looks like it has 2 eyes sticking out instead of "ears"
Just a quick update... I found a few more yesterday and picked them out of the tank. They were all around the same size. Did some more looking around and found this...
i just got a mushroom rock today and found what I think is a White Sea slug it has no shell and has two black eyes it also has what looks like a white foot under it. It is about 1 inch long. Please let me know if you know what this is and if it is reef safe or if I should remove it. Thanks