Bacillus megaterium is a gram-positive, aerobic bacterium that forms spores with radiation resistance 36 times greater than E. coli. These rod-shaped bacteria, often found in oil, have round ends and occur singly or in short chains, measuring 1.2-1.5 µm by 2.0-4.0 µm. The spores are oval, 1.0-1.2 µm by 1.5-2.0 µm, and located at the center or near the end of the cell.