Ambergis is a substance you get from a sperm whale's intestines when the whale has been eating squid and their beaks have irritated the walls of his innards. It was a very popular ingredient in perfumes though it is hard to imagine that it smells good. Ishmael talks lots about it in Moby Dick. Probably just as headily perfumy as musk, which is a glandular excretion from a male musk deer.