Tyrian purple (Ancient Greek: πορφύρα porphúra; Latin: purpura), also known as royal purple, imperial purple, imperial dye, or simply tyrian, is a reddish-purple natural dye. The name Tyrian refers to the city of Tyre in ancient Phoenicia (modern-day Lebanon). It is secreted by several species of predatory sea snails in the family Muricidae, rock snails originally known by the name Murex (Bolinus brandaris, Hexaplex trunculus and Stramonita haemastoma). In ancient times, extracting this dye involved tens of thousands of snails and substantial labour, and as a result, the dye was highly valued. The coloured compound is 6,6'-dibromoindigo.