This strange organic-looking specimen is a lustrous, sub-metallic black sculpted mass of todorokite. It formed when metal-rich subsurface waters emerged from the face of the cliff where microbes exploit the chemical richness of the waters by oxidizing the metals and precipitating minerals as a byproduct! This is the finest example in the world, in Alex and the discoverer's opinions, for a thumbnail example. Included is a letter on this specimen from Robert Hazen, Ph.D., at the Carnegie Institute in Washington, D.C. (whose teams collected these for study on this strange bio-mineral). We actually obtained this directly from Hazen at the time, after they had enough for study, and the funds raised by selling them publicly made for more funding for research on the material. This was the single best thumbnail specimen recovered, in our opinion as well (circa 2012-13). Chesapeake biominerals, including hollandite, todorokite, romanechite, birnessite, and other unusual manganese and iron species, form when metal-rich subsurface waters emerge from the face of the cliffs along the western shore of Chesapeake Bay. Microbes exploit the chemical richness of the waters by oxidizing the metals and precipitating minerals in beautifully sculpted masses. The resulting specimens containing mixed amounts of these related species, such as those you see here, are among the finest examples of their style anywhere in the world and are unique in their aesthetic appeal and scientific interest. A portion of all sales of this material went to to support the study of Chesapeake Bay geology through the laboratory of Dr. Robert Hazen. Alex printed out my early posting of these, as well as documents from Hazen, which accompany the specimen.