Most quantitative metabolites are digestibility reducers that make plant cell walls indigestible to animals. Some bird species also occasionally regurgitate pellets of indigestible matter such as bones and feathers. Many legumes contain toxic and indigestible substances which may be removed through various processing methods. Maize contains lipid transfer protein, an indigestible protein that survives cooking. The stomachs of captured whales often have indigestible squid beaks inside. The indigestible wax acts as a laxative in humans. Like other birds of prey, Eurasian sparrowhawks produce pellets containing indigestible parts of their prey. Wide distribution occurs due to the excretion of the indigestible seeds by birds and mammals. The cilia of the lophophore can change direction to eject isolated particles of indigestible matter. Additionally, some varieties of fat-free chips have been made using artificial, and indigestible, fat substitutes. Dark honeys and honeydews have greater quantities of indigestible matter. It ejects pellets of the indigestible parts, in the manner of an owl. Sometimes, a pellet of bones, scales and other indigestible debris is coughed up. Some wild species are toxic, or at least indigestible, when raw. Indigestible remains of prey are expelled through the mouth.