Though there is increasing understanding of the ecology, diversity and activity of microbial life in deep sediments, little is known about the microbial life inhabiting deep oceanic crust. It is not yet known what proportion, if any, microorganisms in the rock biosphere are actively growing. The work proposed in this fellowship application will be to identify and quantify active microbial biomass from Atlantis Massif oceanic crust samples collected during IODP 357. Fluorescence based microscopy techniques (BONCAT) will be used as a means to sort active cells using flow cytometry for downstream 16S rRNA gene, metagenomic and single celled sequencing. This combination of approaches for presents great potential to reveal if communities are actively growing in/on the rock, and will give insight into the taxonomy and function of active microorganisms in the Atlantis Massif deep oceanic crust.