Tyrian purple

So that's what's going on with "purpur". "Purple" used to be more of a crimson.

For example, Tyrian purple. And huh, two shellfish:

One of the trade secrets of the Tyrians probably was the mingling of the dyes from the two different shellfish; for the Murex, if used alone, produced a dull, dark purple and the Buccinum, a red tone which faded easily. Buccinum red was less in demand -- 200 pounds of Buccinum dye brought only 111 pounds of the Murex. It was by immersing a cloth, first in the dye of the Murex and then in that of the Buccinum, that the dark, rich color known as Tyrian purple was obtained. It has been described as "the color of coagulated blood, but when held up to the light showing a crimson hue."