Invasion of the Black Slime

[Catsmate]

It's creeping black slime that can't be killed and it's spreading. Technically it's a biofilm, part algae, part bacteria and part fungus, and it was detected by the US National Park Service earlier this month, befouling the Jefferson Memorial. It's also been detected on the Washington and Lincoln Memorials, and on tombstones in the Congressional Cemetery. And around the world, from Egypt to the Angkor Wat temples in Cambodia.

Hmmm...

Washington Post.
IFL science.