Supposedly look like brains
The Aquavirius Maggot is supposedly a creature that resembles a brain. While in the Department of Mysteries in the Ministry of Magic Luna Lovegood incorrectly identified the pale blobs floating in the brain tank in the Department of Mysteries as being Aquavirius Maggots though they were in fact just brains. The Aquavirius Maggot is one of the many strange creatures in which Luna Lovegood and her father believed in though not many others do.
- Harry Potter and the Order of the Phoenix (Mentioned only)