Denise Shirley of Mosgiel asks :-

Whilst tramping around the coast we found a waxy blob washed up. Could this be ambergris?

Ewan Fordyce, a fossil geologist at Otago University, responded.

As a child, I heard of ambergris: a rare and valuable waxy substance from the gut of the sperm whale, cast up on beaches, and prized as an ingredient for perfume. The name ambergris means grey amber, in allusion to the plant amber that washes up on some sea coasts. In the 1700s, ambergris was identified as coming from the sperm whale and, according to the literature, ambergris has been recovered more commonly from whale intestines than from beaches. Direct from the gut, ambergris is dark, soft, and smells unpleasant. It may have squid beaks embedded, leading to the idea that the ambergris protects the gut against irritants. (Squids are a prime food of the sperm whale, the only species known to produce ambergris.) Older ambergris, which floats in cold water, is harder and lighter in colour, with a subtle, sweet, tenacious, pleasant and musky odour. Lumps of ambergris may be potato-shaped, usually weighing 0.1 to 10 kg, and originating from whale faeces. There are reports of pieces weighing 421 kg (recovered from a whale gut) and 635 kg (presumably "freed" after a whale died).

There are many scientific articles on ambergris and its derivatives. Ambergris was once commonly used in perfumes, because of its property of fixing or "holding" smells. It has been used as a medicine and aphrodisiac. Research on natural ambergris shows that it includes cholesterol-like compounds. Such work has led to synthesis of artificial compounds that mimic the original. Ambergris components have been reported from plants including southern pines - podocarps - and are known because of their stimulating smell to influence the behaviour of some mammal species.

There are some simple tests for ambergris: it floats in seawater, it smells musky, it dissolves in alcohol, and it melts in hot water. A hot needle can be plunged into ambergris, instantly forming a dark tacky melt that leaves a sticky residue on the needle.