Russian cosmonauts have discovered something remarkable clinging to the outside of the International Space Station: living organisms.

The microscopic creatures appeared during a space walk intended to clean the vessel’s surface, and were allegedly identified — incredibly — as a type of sea plankton. This is big: According to Sploid, Russian scientists are both “shocked by [the] discovery and can’t really explain how [it] is possible.”

More details including pictures can be found here:

http://mic.com/articles/96920/astronauts-just-found-life-in-outer-space-and-scientists-aren-t-sure-how-it-got-there