Very cool critters, but not for the average aquarium. Notice I typed aquarium, not aquarist!
They require insane amounts of particulate foods. They have photosynthetic qualities, but rely on food capture for most of their sustenance. Well established refugiums can house them for a while, but without frequent daily dosings of phytoplankton and the like, they inevitably starve to death. Most aquariums cannot handle the abusive amount of foods the Renila reniformis demands.
Fish do not read books, nor care what we think.