Tyrian purple (Greek: πορφύρα, porphyra, Latin: purpura), also known as royal purple or imperial purple, is a purple-red dye which was first produced by the ancient Phoenicians in the city of Tyre. Tyrian purple was expensive: the fourth-century BC historian Theopompus reported, "Purple for dyes fetched its weight in silver at Colophon" in Asia Minor. The dye substance occurs naturally, but must be harvested by humans. It consists of a fresh mucus secretion from the hypobranchial gland of a medium-sized predatory sea snail, the marine gastropod Murex brandaris, currently known as Bolinus brandaris. This species is commonly called the spiny dye-murex, and it is a species in the family Muricidae, the murex or rock shells. The current range for this species is the "central and western Mediterranean". In Biblical Hebrew, which like Phoenician is a dialect of Canaanite, the Tyrian purple-red dye extracted from the Murex brandaris is known as shani שָׁנִי [ʃɔni], but usually translated as 'scarlet'. Another dye extracted from a related sea snail, Hexaplex trunculus, could produce a purple-blue color called argaman אַרְגָּמָן [argɔmɔn] (translated 'purple') when processed in shade, or a sky-blue indigo color, called tekhelet תְּכֵלֶת [təxelɛθ] (translated 'indigo') when processed in sunlight.