Mold

Not to be confused with the level type based around this element or the episode with an almost identical name.'

The rainbow rapid (also known as rainbow rapid mold or simply mold) is an element in Candy Crush Saga. It was released along with Rainbow Rapids levels, which is its corresponding level type.

Properties

It is needed to make rainbow candies.
Rainbows must reach the mold in order to make rainbow candies. To make the rainbow rapids reach the mold, you must clear all the blockers blocking the path. Blockers (except for crystal candies) can stop the flow of the rainbow rapids.
Once the rainbow rapids have reached the mold, the mold will fill up and produce a rainbow candy, which is then automatically collected. The rainbow rapids then disappear, along with its corresponding cannon and path.
Currently, the rainbow rapid mold cannot be encased in any encasing blockers. Assuming that it was possible for it to be encased, it's possible that the mold would need to be unlocked before the rainbow could fill it up.