A childhood belief about under my bed

I used to believe that there was a group of monsters who met under the bed that I slept in at my grandmother's house. There was a vampire, a witch, an octopus, and several unidentifiable creatures, and there meetings always seemed to be when I was visiting. I thought they could see through the mattress, sheets, and my pajamas, and my mother had told me not to let anyone see me naked, so I would always wrap up in layers and layers of covers, even when it was hot.