Just to be really really precise: while Snowball Earth periods were long, they did not last but a small part of the Precambrian.

The one Snowball Earth era we can be reasonbly certain about was maybe between c. 800 and 580, but certainly between 745 and 635 million years Before Present (BP), and was actually 2-5 successive Snowball Earth periods (e.g. freezing and thawing up), each a few to a few dozen million years long.

There is a hypothetised earlier Snowball Earth period 2.3-2.2 billion years ago. (The Earth is 4.567 billion years old.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}