During a routine spacewalk on the ISS, astronauts meant to clean the exterior of the space station but ended up finding living organisms. They had expected to find nothing more than fuel residue but instead found sea plankton they believe came from Earth. However, they can't figure out how they got there or how they even survived.
The little creatures in question are most similar to tardigrades here on Earth but no one has been able to confirm this theory since they can't even explain how they got there. Tardigrades are also know as water bears are very resilient in nature. They can withstand radiation amounts hundreds of times higher than the lethal dose for a human, and pressure six times the amount that is found in the depths of the ocean and space.
It is interesting to see that any kind of organism can survive the harshness of space where there is zero gravity, crazy temperature conditions, and unshielded cosmic radiation.