The collected samples of Geodia species were used to identify if they were reproductive and understand which genes are expressed during gametogenesis. Specifically, specimens fixed in glutaraldehyde solution, were processed for histological analysis to observe gametes in the sponge tissue. Once, we identified male, female (while in gametogenesis) and non-reproductive specimens, we used the RNAlater fixed samples to extract RNA from those specimens. Then, we prepared cDNA libraries, sequenced them with illumina nextseq and we did differential gene expression analysis in order to compare the expressed genes in male vs female specimens and vs non-reproductive specimens. The goal was to understand the molecular machinery of gametogenesis in sponges from an evolutionary point of view.