I always imagined them as some kind of "plants", given how they're described to replicate/combine and how they're dried up and stored and later rehydrated...

Here you go:

https://www.mentalfloss.com/article/56755/16-amazing-facts-a...

In The Redemption of Time, Baoshu offers his view.

It’s “only” a fan fiction, albeit approved by Liu Cixin.

It nonetheless gives a nice — and as expected — unexpected description of them.

For me, I pictured them as the water aliens from Futurama's "My Three Suns".

Daleks with a strobe light on top.