Oh, and regarding the survival of life through a Snowball Earth state, there's been some interesting discussion of potential refugia such as polynyas [1] and cryoconite ponds [2,3], though for context the most advanced multicellular organism I've seen anyone propose prior to the last snowball is still only a sort of sponge [4]
[1] https://en.wikipedia.org/wiki/Polynya
[2] https://en.wikipedia.org/wiki/Cryoconite
[3] https://onlinelibrary.wiley.com/doi/abs/10.1111/gbi.12191