Dr. Annamarie Johnstone writes, “The ‘blue berries in the Opportunity Rover image may be fruticose type rock lichens (symbiotic plants composed of fungi and algae.) Forming a mutualistic relationship, the dense skin of the fungus protects the interior algal cells from desiccation, in turn, the photosynthetic algae, using sunlight, and produce food for the fungus. Lichens are brightly colored pioneer plants in an ecosystem, capable of “shutting down” metabolically, when subjected to unfavorable environmental conditions. As a result, they are able to survive extreme heat, cold and drought.
Lichens grow only when moisture is available, so the amount of moisture governs their rate of growth. Composed mainly of carbohydrates with a small percentage of protein, rock lichen species can be a food source for animals, man, and perhaps Martians. The frigid community is made up mostly of primitive creatures called Cyanobacteria, which live in tightly-woven groups called microbial mats. The microbes produce chemicals that act as anti-freeze and UV shields, protecting them from frigid temperatures and from sunlight. I remain convinced that the Mars “Blueberries” are fossilized Cyanobacteria (also known as blue green algae) in an inclusion layer of mineralized sediment that can be sectioned and observed. Thanks to Dr. Annamarie Johnstone.