The Augusta Chronicle reports the material looks like a cobweb.
The senior technical adviser for the Savannah River National Laboratory, Christopher Berry, says genetic analysis shows it's mostly bacteria although some of the DNA strains are unknown. It was first observed about a year ago among old fuel assemblies submerged in a basin where nuclear materials from research reactors are stored.
The growth is harmless, but scientists want to study it more because of its unusual environment. They are trying to find out what it uses for food.
Such colonies are rare, but have been observed in a Canadian reactor and in the spent fuel basin at Three Mile Island in Pennsylvania.