Hive resin

Xenomorphs secreted a resin which a group of students once used to decorate the surfaces of their block of flats, to give it the appearance of, as Simon Frederson put it, "knobbly, black, and unpleasantly organic shapes and orifices" and "very ugly and retro". (PROSE: So Vile a Sin)

Behind the scenes
The resin that was referenced in So Vile a Sin was "Hive resin", which, in the Alien franchise, is the resin secreted by Xenomorphs to build their nests, often covering the walls of spaceship interiors.