Also known as (grey) ambergris (Ambra grisea), it is a substance secreted from the sperm whale’s gall bladder. The grey variety (which with age turns black) should be distinguished from yellow amber, which is fossilized tree resin. Both have been used in perfumes and medicines, but only yellow amber was (and still is) prized as a gemstone. The ancient Greeks knew it as elektron, which gave the word ‘electricity’, initially meaning static electricity because of its capacity to attract other materials after friction. One of the earliest references to the importation of ambergris can be found in the 9th-century travel book Akhbār al-Sīn wa ‘l-Hind (أخبار الصين والهند, ‘News from China and India ’) where people of an island called Lanjabālūs in the Sea of Harkand (Bay of Bengal) traded ambergris for iron with Arab merchants. Ambergris was used as an ingredient in medicines, incense tablets, and perfumes. In cooking, it appears as a fumigant to scent a bowl or as a flavouring in dishes. Ibn al-Bayṭār, who called ambergris ‘the king of scents’, recommended it (by mouth, in a cream, or as a fumigant) as a remedy for flatulence, migraines, and to strengthen the joints and stomach. He added that ambergris immediately increases the intoxicating effect of wine.