Why did blue marks suddenly appear on the toilet wall of the bathroom? Is there a virus?

This is a normal situation, there are people upstairs who comb their hair by the windowsill and throw the hair off the wooden comb.

The combined result of long-term immersion in water and dirt (including the resulting bacterial action).

It is possible that when the paving was first paved, the joints were not hooked with professional grouts, but the mortar cement was directly smeared, and the brick joints were naturally dirty, discolored, mildewy and smelly after a long time. Although the joints cannot be completely avoided with a good grout, if you generally pay attention to cleaning, it is not as serious as you said, and at most the brick joints are a little discolored. >>>More

Probably Malu, a millipede that prefers darkness and dampness. >>>More

That's due to the smell of the bathroom being dark and damp. >>>More