Exodus 25:4

Scarlet twice dyed. Aquila and Symmachus have transparent. This colour is often confounded with purple, as our Saviour's robe is styled scarlet by St. Matthew xxvii. 28; and purple by St. John xix. 2. It was dyed with a worm called shani in Hebrew. (St. Jerome, ep. ad Fabiol.) --- Fine linen, byssus. Hebrew shesh, "or six folds," or it may mean cotton, which was highly esteemed by the ancients; (Arabic version; Herod.) and it is not probable that Moses would have passed over it unnoticed. (Calmet)