Formaldehyde is very widely used in the process of embalming. It is a fixative, and kills bacteria, fungus, and insects. It prevents decay by keeping decomposing microorganisms from surviving on and in the cadaver. It also cures the tissues it is used in so that they cannot serve as nutrients for these organisms. While formaldehyde is a good antiseptic, it has certain disadvantages as well. When used in embalming, it causes blood to clot and tissues to harden, it turns the skin gray, and its fumes are both malodorous and toxic if inhaled. However, its abilities to prevent decay and tan tissue without ruining its structural integrity have led to its continued widespread use to this day.