Lichens, a fungus-algae composite organism that grows on rocks and trees across the world, are hardy and can survive just about anywhere on Earth. As it turns out, they can also latch onto just about anything, including nuclear fallout.
According to , lichens taken from areas near nuclear test sites in the 1940s and 1950s contained radioactive isotopes unique to those bomb tests. The isotopes included traces from the Trinity test site, where the atomic bomb was tested under the Manhattan Project in the 1940s, as well as the Nevada Test Site, where atmospheric nuclear weapons tests took place from the 1950s into the 1960s.
All in all, lichen samples were taken from 10 locations in New Mexico. The samples were then dried out and burnt, with the chemical composition tested afterward. The lichen appeared to absorb fallout from top soil and internalize it.
Lichens, due to their ability to absorb chemicals from soil and other surroundings, are often used to test for environmental pollutants and heavy metal contamination, but this is one of the first tests from nuclear testing areas.