The microstructural characterization of Mellita Eduardobarrosoi sp. Nov, a marine skeleton, subjected to thermal treatments of 4008, 6008, 8008, and 9008C is presented. The results show that this species has pores with diameters ranging between 10 and 20 mm and is constituted mainly of O, Ca, C, and Mg as (Ca, Mg)CO 3 . This particular compound transforms into CaO when heated higher than 8008C. This change is observed in FTIR spectra as the disappearance of two absorption bands at 875 cm 21 and 878 cm 21 , which correspond to loss of CO 2 .