These oligosaccharides pass undigested through the stomach and small intestine. Fat-soluble nutrients consumed with olestra products are excreted with the undigested olestra molecules. The material that remains undigested and unabsorbed passes into the large intestine. The undigested vegetable contents of a prey animal's stomach and intestines are typically avoided. Ravens may also consume the undigested portions of animal feces, and human food waste. Chromatography can be used to separate and identify undigested sugars present in faeces. Waste and undigested matter is excreted through this opening. Sometimes undigested food may make an appearance in the feces. They sometimes eat their own green, faecal pellets to recover undigested proteins and vitamins. Cormorants regurgitate pellets containing undigested parts of their meals such as bones. Bacterial fermentation of undigested polysaccharides produces these. Most platyhelminths have no anus and regurgitate undigested material through the mouth. Like kingfishers, bee-eaters regurgitate pellets of undigested material, typically long black oblongs. The undigested nut can be easily gathered from emu droppings. Undigested sedge leaves have occasionally been found in Ethiopian wolf stomachs.