Worms for Mars

Simulated "Martian gardens" allow NASA scientists to test which plants can be grown on Mars. This photo shows the results of a preliminary study on lettuce. From left, lettuce seeds grown in potting soil, the Martian simulant with added nutrients, and the simulant without nutrients.

In what could be an important milestone for future farmers on Mars, two healthy baby worms were recently born in simulated Martian soil. The births took place in an experiment that is helping scientists understand how human settlers might one day grow crops on the Red Planet.
Martian soil simulants — made from volcanic terrestrial rocks — and pig manure, to which he added live adult worms. University officials said in a statement that the infant worms are the first offspring of adult worms to be born in a Mars soil simulant.
Worms begin the breakdown of organic matter, which is continued by bacteria. That leads to the release into the soil of such vital plant nutrients as nitrogen, phosphorous and potassium, according to the statement from Wageningen University and Research.
When worms eat organic matter, they also eat the soil. Since there isn't much weathering of Martian terrain, sharp edges in its soil do not get worn down (the way they do on Earth) and may cause worms harm, according to the statement. The presence of heavy metals in Martian soil could also be a long-term problem for worms, which would require lengthier experiments to address properly, the researchers said..... Source..