iron oxide or sulfide. The MTB may either have iron oxide or sulfide but not both. Certain subgroups of the Pseudomonadota in the domain of Bacteria have been found through analyses of the MTB’s RNA to only use iron oxide which is the more common material. Another smaller subdivision of the Pseudomonadota that are part of a sulfide reducing bacteria use iron sulfide. Scientists say this suggests independent evolution of the same trait. The magnetite crystals have been observed in three different morphologies, cuboid, rectangular, and arrowhead shaped. Size of magnetite crystals Magnetotactic crystals range anywhere in size from 30 nanometers to 120 nanometers. This size allows them to be magnetically stable and to help optimize the MTB ability toward magnetotaxis. The single domain crystals have the maximum possible magnetic moment per unit volume for a given composition. A smaller size would not be as efficient to contribute to the cellular magnetic moment, the smaller size crystals are superparamagnetic, therefore they are not continuously magnetic. Crystals exceeding 120 nanometers can form magnetic domains in opposition to the desired direction. While a single magnetosome chain could appear to be ideal for magneto-aerotaxis, a number of magnetotactic bacteria have magnetosomes or magnetosome arrangements that depart from the ideal. A reported example includes large magnetosomes (up to 200 nanometers) found in coccoid cells in Brazil. These cells contain enough magnetosomes that the calculated magnetic dipole moment of the cell is about 250 times larger than that of a typical Magnetospirillum magnetotacticum. Some bacteria have magnetosomes that are not arranged in chains, but the magnetosomes are clustered on one side of the cell. In this arrangement, the shape anisotropy of each crystal provides the stability against remagnetization, rather than the overall shape anisotropy in the magnetosome chain arrangement. These non-ideal arrangements may lead to additional, currently unknown functions of magnetosomes; possibly related to metabolism. Collapse When the magnetotactic crystals are in an unstable arrangement the whole magnetosome will collapse without additional support. The collapse can occur during diagenesis and dolomitization. The magnetosome shape and elastic properties of biological membranes are what is holding the chains together, as well as the linearity and the connection to the cytoskeleton. With how much the geometries effect the stabilization of the chains of magnetosomes shows that they are intrinsically unstable. The cell wall and associated membrane structures have been thought to act to prevent magnetosome chain collapse. There