Some fossil traces mainly related with the organic action of Mollusca (Gastropoda, Bivalvia) have been studied in the Bajo Guadalquivir Basin (Lower Pliocene). This activity feflecta boring, scraping and encrusting behaviours that respond to feeding and dwelling needs. From this study, a new ichnogenus: Renichnus is proposed to name a kidney-like trace produced by the encrusting activity of some organisms.