The answer is lichens. Lichens are not organisms which are prokaryotic. They are an association between a fungus and and algae which is mutually beneficial. This is an example of symbiosis. Both of these organisms have Eukaryotic cells, or cells with an organized nucleus as well as membrane-bound organelles. Sometimes, the association is between a fungus and a cyanobacterium called Nostoc however, this bacteria is not an Archaea, but a Monera. Lichens can grow on bare rock, walls, buildings, etc. The fungus surrounds the algae cells or the cyanobacteria cells and they in turn can provide nutrients as the algae is photosynthetic and the bacteria can fix nitrogen. The fungus are moist and retain water and provide a substrate for the others to grow on.