A couple hit an unlikely jackpot last week when - lured by the stench of rotting fish - they stumbled across a lump of whale detritus on a British beach. Ambergris, a product of the digestive system of sperm whales, has long been deployed by perfumers to add a certain something to their wares, despite its unpropitious air.Eagle-eyed and clearly robustly nosed engineer Gary Williams described his find as smelling "like a cross between squid and farmyard manure".Nevertheless, this hideous 1.4kg Morecambe Bay nugget is expected to sell for £50000 (more than R1-million), a windfall with which Williams hopes to buy a caravan.He and wife Angela are in negotiations with prospective buyers in France and New Zealand. Another 2.7kg lump was found in the area three years ago, valued at £120000.Despite conservation fears, ambergris remains on ingredient lists - in Dior's Poison and Creed's Green Irish Tweed, for example - presumably in its synthetic form of ambroxan.Those of us who have inhaled it will not forget the experience.Fragrance entrepreneur Roja Dove once unveiled a block for me over cocktails at Claridge's - an act that we were rather more enthusiastic about than our fellow drinkers.Traditionally considered to be vomitous in origin, now thought to be faecal, ambergris may bob about in the ocean for 30 years before being washed up. As it floats, a white film forms on its greyish exterior as it oxidises in salt water. The lighter the hue, the longer the piece will have been at sea and the lighter and sweeter its scent; lighter and sweeter being relative terms for an object that can only be described as dank, fishy and disturbing - if rather unearthily fantastic.And, yet, what poetry it becomes in the alchemy of perfume.James Craven, historian and archivist for perfumery Les Senteurs, enthuses: "Ambergris lends a scent a tenacious depth, richness, opulence, smoothness, ambiguity and an unsettling 'do I love it, or hate it?' quality."It prompts the intriguing thought: 'I am divinely scented and delicious, but am I entirely clean?' Its use can seem rather mythical on investigation..."Craven continues: "And I can vouch for its appearance in the Coronation Oil, the chrism made for Charles I and more or less replicated for Elizabeth II. I have smelled it: neroli, spices, rose and real ambergris."Still, whale excrement isn't the half of it. People may like to think of perfume as being all hearts and flowers. However, it is its seedy, animal underbelly that makes us crave it. Countless classics contain more than a glimpse of "something nasty in the woodshed": primitive, distinctly feral base notes that belie the bouquets in their upper spheres.Many of perfumery's most venerable creations owe their sensuality to the use of animal ingredients with a certain "spray" element. There is civet, a faecal paste extracted from the anal glands of the civet cat, traditionally harvested by poking caged cats where the sun doesn't shine. Today's animal magic mostly comes in synthetic guise.However, the gutsiness of fragrances such as Chanel No 5 and Guerlain's Shalimar is owed to this tradition.Musk secreted from the sheath gland of the musk deer is at its most redolent in Dana's Tabu. Castoreum, a leathery emission from the genital scent sacs of the castor beaver (and my own personal favourite) is evident in Balmain's Jolie Madame.Perfumers have never been backward about coming forward in using such ingredients to conjure life's wilder side.Generations of scent sensualists have endeavoured to add outré elements to their concoctions, be it sweat, semen, underarm odour, soiled skin, clammy saddles, breast milk, curry, petrol, alcohol, rotting roses, oral abscesses, dirt, tobacco, industrial buildings, lunar landscapes, and - in the case of enfants terribles perfumers Christoph Hornetz and Christophe Laudamiel - the scent of a virgin's navel.Should all this come as an unpleasant surprise, Craven provides comfort: "We humans explore ourselves through scent, and find our shadow side - that often resented, even sinister, darker self. And so perfume is by no means all sweetness and light, moonbeams and gardenias."..