Bacillus megaterium is a rod-like, Gram-positive, mainly aerobic spore forming bacterium found in widely diverse habitats. It has a cell length of up to 4 µm and a diameter of 1.5 µm, which is quite large for a bacteria. The cells often occur in pairs and chains, where the cells are joined together by polysaccharides on the cell walls. This species has been recently transferred into the genus Priestia. The correct nomenclature is Priestia megaterium.