Protein metabolism in marine gastropods produces ammonia as its end product, making it an ammonotelic animal. This ammonia is extracted and excreted from the body by the right nepridium found in the mantle cavity of C. parthenopeum. The hemocoel runs around it where the nepridium absorbs the excretory waste from it. It is a blind sac with folded walls aimed at increasing surface area for absorption and excretion. The nepridiopore is located at the downstream side of the gills at the rear of the mantle cavity to avoid fouling the inhalant water passing over the gills and osphradium. The wastes are then washed out by the exhalant current (Ruppert et al., 2004).