Seeds also do not change or exhibit life, and can remain in that state for years, even centuries. But then, with water, they start to grow.
Could it not be considered the same mechanism, except that as these organisms are simpler than seeds and retain their shape (ie do not grow and change) and it is possible for these microscopic creatures to revert to the initial 'seed state' then animated life repeatedly?
I've always found it fascinating that I could plant many spice seeds (e.g. mustard) as long as their container said "not irradiated", and they would sprout and grow just fine, several years after buying them. I.e. they are still technically alive, and can stay as such for many years, which is just amazing life resilience.
That said,
> ...except that as these organisms are simpler than seeds...
I wouldn't say any animal that can move around to be simpler than seeds. IMHO by any definition animals are a big jump up in complexity over plants.