Ambergris is a solid, waxy substance of a dull grey color produced in the digestive system of sperm whales. Freshly produced ambergris has a marine, fecal odor, but as it ages, it develops a sweet, earthy fragrance. The substance has recently been highly valued by perfume makers as it allows the scent to last much longer, although it has been mostly replaced by synthetic ambroxide. Ambergris has historically been used in food and drink. It has been used as a flavoring agent in Turkish coffee and in hot chocolate in 18 century Europe. During the Black Death in Europe, people believed that carrying a ball of ambergris could prevent them from contacting plague. This was because the fragrance covered the smell of the air which was believed to be a cause of plague. During the Middle Ages, Europeans used ambergris as a medication for headaches, colds, epilepsy and other illnesses. Throughout the 19th century, millions of whales were killed for their oil, whalebone and ambergris to fuel profits and they soon became endangerd as a species. Ambergris, although is not harvested from whales, many countries also ban the trade of ambergris as part of the more general ban on the hunting and exploitation of whales.