My bathroom ceiling

This story begins two years ago when the apartment above mine got a new bathroom. The walls that adjoin these apartments are 6 inches thick - each apt gets 3 inches for their wiring, pipes etc. But the folk upstairs coveted those three inches, and wanted them for their new bathroom. So they took down their wall, shoved everything on to their neighbour's side, tiled up against his wall, and luxuriated in their extended bathing space. Naughty.

Earlier this year, their neighbour gutted his place and moved all the rooms around. When his electrician was rewiring, he broke through the three inches, and discovered he'd broken through grout. And he could see through to a bathroom on the other side... Well they couldn't complete their building work; there was danger of flooding/electrocution and lots of arguments, which were still ongoing when I left for Ireland.

So I came back, and had a shower, as you do. And then I looked up - there were long water stains across the whole ceiling, bits of plaster were falling out at the corners, and there were knobbly bits on the ceiling.

At first I thought the plaster was swelling with the water. Then I thought of fungus, of how in House MD when someone's critically ill, they always go and check their home for spores...

And the following morning, all was revealed:

And what's more, if my bathroom's affected, so is German Porn Man's. We're all waiting for him to notice...