[eh_why_not]

Seeds were also the first thing that came to my mind.

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.

[falcor84]

Plants in general have much larger genomes than animals, and that's clearly a definition of complexity.

[immibis]

That just means they have less selective pressure to reduce it - possibly because they are simpler. Genome size isn't correlated much without complexity. Obviously it provides an upper bound, but a lot of genes are repeats.