+1nudibranch .... Generally starve to death in home aquaria as it's next to impossible to provide them with the needed diet.
not a filter feeder. Possibly hypselodoris bullocki .
nudibranch tend to feed on one specific type of item (not just any sponge, but species of sponge) and generally starve to death in home aquaria as it's next to impossible to provide them with the needed diet.