Recently I have noticed rust/orange colored spots on the ceiling of my shower and the ceiling just outside it. I'm noticing them being there from moisture when anyone takes a shower. Does anyone know what could be causing it or what it even is? I'm wondering because I would like to have plants in my bathroom because it gets excellent light all day through the window and if this stuff would harm the plants??? Or even us and our pets . thanks for any info! I've done some looking online but have come up with nothing. :(