Murex or, much less interestingly, rock snails, are a genus of tropical-sea dwelling predatory molluscs.
Tyrian or Royal Purple, a deep red with a purple tint, is a dye made from the mucus of these creatures. First used over 3000 years ago, the dye was highly prized by the Romans. It was difficult to extract and therefore expensive and, unlike many other natural dyes, the colour improved with age and exposure to sunlight.
Use of the dye continued until the mid-15th Century when Europeans turned to cheaper sources for red and purple.
The word murex is Latin – the Greek word is myax, ‘sea mussel’. Myax is related to the word mys, which in Greek means both muscle and mouse.
This link between muscle and mouse exists in Latin, German and Arabic. The connection developed from the idea that many muscles, especially biceps, were considered to have ‘the shape and movement of a mouse’. Thus muscled and mousey come from the same base word.
And the predatory murex? Probably more mouse than monster. Far more dangerous the harvesters – who needed 12000 murex to make two grams of dye – or the emperors who wore the robes imbued with the purplish colour.