Most unusually for a ghost, it seems Myrtle does have some control over physical matter; apparently her haunting of the bathroom has rendered it unusable, mainly because she keeps flooding the place when she gets depressed. This is necessaryuseful to the story in two respects: Mrs. Norris is Petrified (in [[../../Books/Chamber_of_Secrets/Chapter_8|Harry Potter and the ChammberChamber of Secrets]]), rather than being killed, because she sees the reflection of the Basilisk rather than seeing the Basilisk directly. The image is reflected in the water that Myrtle has caused to flood out of the bathroom because she was so upset at the insults lobbed at her by [[../Peeves/]] at [[../Nearly Headless Nick/]]'s Deathday party. Additionally, it is Myrtle's unwelcoming presence in the washroom that allows Hermione the time and space to make [[../../Magic/Polyjuice_Potion|Polyjuice Potion]]; nobody willingly goes in there more than once, after being subjected to Myrtle's aggresive depression.
