I thought that... but when she said "kept growing" that clicked in my brain as if she was repeatedly cleaning it out of there. I bet it wouldn't grow mildew if she put it near sunlight. But... uh... then... ibthinggrowsalgae.

Edit: Ima get 1 of those things and see. If I can keep him out of the vet'$ office while breaking his furry ass of getting in my porcelain fixtures, I will. I don't want his post-litter-box paws on my toilet seat, and closing the bathroom door is part of what led him to his first vet visit. I gotta get him hydrated however I can.