Ceiling Cat's bath
Yes, it could be Ceiling Cat's bathing area.
Though the thought of what Mulder and Scully investigated in the episode "Ice", is pretty scary.
Then again, it could reveal an organisim that can take over and imitate a host body, and imitate it perfectly. So long as we have Kurt Russell on hand we should be ok.
Or maybe they find a bunch of shiteating space-weevils, that Morgan Freeman will blow to kingdom-come.
Or perhaps they discover a delicious mysterious goo that they market as yummy dessert, but which turns eveyone into mindless zombies. But at least it's low calorie and tasty.
It could even releave an ancient pyramid, build by man, infected with Aliens and played on by Predators. So long as we have Lance Henriksen on hand we should be ok.