Organic-derived materials used during clay preparation prior to pottery shaping are frequently collected by potters in areas related to their day-to-day activities, such as farming lands, herding areas or places devoted to food processing. Features of organic origin in ceramic pastes may thus provide significant social, cultural and economic information regarding organic resource exploitation in past production systems. We herein present the results of a microanalysis specifically designed to characterise both porosity and bioclasts in ceramic pastes. Our study focuses on the ceramic assemblage of Koumbi Saleh (Mauritania, 5th–17th centuries AD). Organic-derived features observed in this ceramic material have been characterised through optical microscopy performed on thin sections, coupled with bioclast extraction and characterisation. On the basis of comparisons with experimental reference data, various organic components have been identified. These results shed light on a large variety of tempering materials and outline possible links between pottery manufacture and other production systems.