In the clouds on Venus, scientists say there is a gas that could potentially signify life, according to CNN. The gas, phosphine, is a flammable, toxic gas produced by bacteria that requires no oxygen. It is found on Earth in wetlands, swamps, and in animal guts. It has an unpleasant smell similar to garlic or decaying fish.

“Something completely unexpected and highly intriguing is happening on Venus to produce the unexpected presence of tiny amounts of phosphine gas,” Sara Seager, study coauthor and astrophysicist and planetary scientist at Massachusetts Institute of Technology, said.

Phosphine gas can also occur when organic matter breaks down. It is always associated with life; therefore, is difficult to make by normal geological or atmospheric action, according to Scientific American.  By the time the gas reaches a concentration where people can detect its smell, the gas can cause lung damage.

The temperatures on the surface of Venus are 900 degrees Fahrenheit, and the planet is surrounded by sulfuric acid clouds. However, scientists say the clouds where the phosphine gas was found are relatively balmy with sunlight, as well as temperatures and atmospheric  pressure similar to Earth.

Venus is the brightest planet the naked eye can see aside from the sun and moon. While little is known about the planet, NASA is currently considering proposals for two missions to Venus for funding under its Discovery Program, the orbiting VERITAS and DAVINCI+.