Scientists believe that ambergris is produced in order to ease the passage of hard and indigestible matter through the whale's intestine, and is normally passed in faecal matter; but that large masses, which may be produced to cope with particularly large indigestible items, may be expelled via the mouth (along with the indigestible item itself). This has led to ambergris being referred to colloquially (presumably by people who regard the use of perfumes as a reprehensible manifestation of vanity) as 'whale vomit'.

When first excreted, ambergris smells strongly of faeces; but after passing from the whale's body it may float on the surface for years. As it does so, it acquires (through oxidation and photodegradation) a sweet, earthy scent – which is what makes it useful to perfumiers.

One of the key chemicals that give ambergris its characteristic odour is ambroxide. This can be produced artificially, which has reduced the demand for ambergris. Even so, the natural substance continues to be extremely valuable. In 2015, a lump weighing 1.1 kg (2 lb 6 oz), which was found on a beach on Anglesey, fetched £11,000 at auction in Macclesfield, Cheshire – home town of this website.

© Haydn Thompson 2017–20