The Hebrew translation for “crimson worm” is the word “towla”.
When the crimson worm is ready to lay its eggs, which is an event that happens only once in its life, it climbs up a tree and attaches itself to it. With its body attached to the wooden tree, a hard crimson shell forms. The shell is so hard and secured to the wood that it can only be removed by tearing apart the body, which would kill the worm.
The worm lays its eggs under its body, under the protective shell. When the larvae hatch, they remain under the worms protective shell so the baby worms can feed on the living body of the crimson worm for three days. After three days, the worm dies, and its body excretes a crimson or scarlet dye that stains the wood to which it is attached and the baby worms. The baby worms remain crimson-colored for their entire lives. Thereby, they are identified as crimson worms.
On the fourth day the tail of the worm pulls up into its head, forming a heart-shaped body that is no longer crimson but has turned into a snow-white wax that looks like a patch of wool on the tree. It then begins to flake off and drop to the ground looking like snow.
But I am a worm (towla) and not a man, scorned by everyone, despised by the people. (Psalm 22:6)
Come now, and let us reason together, saith the LORD: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool. (Isaiah 1:18)