Two distinct pools of B12 analogs reveal community interdependencies in the ocean. - Heal, Katherine R.; Ribalet, Francois; Coyote-Maestas, Willow; Hmelo, Laura R.; Devol, Allan H.; Armbrust, E. Virginia; Ingalls, Anitra E.; Wei Qin; Bertagnolli, Anthony D.; Stahl, David A.; Moffett, James W. (Proceedings of the National Academy of Sciences of the United States of America, 2017)