Are aliens surviving.Some clues have been found on Mars.Other countries have been found with fossils and with dried vegetaton.
Answers (1)
Only if the biology of Aliens has the same atmosphere and temperature requirements as life on Earth.
Assuming they have the same biology as Earth life, they also need to have the same immunity defenses to protect against viruses and bacteria. For example, in H.G. Well's Science fiction classic called "World of the Worlds" the aliens from Mars are unable to survive because they don't have immunity to human viruses, despite having initial success invading the planet.