how do i get this out of my shower
i live in an apartment and it’s had this sort of crack in the corner since we moved in. i don’t remember if the black was there when we moved in. i’ve gone at it with bleach a couple times (assuming it was mildew or mold) and it didn’t do anything. i went at it with white vinegar and dish soap, and still nothing. what is this and how do i get rid of it? is it possible it’s some kind of caulk? it makes my shower look disgusting and unclean