Her main body doesn’t decay, as far as I know. It was treated so it wouldn’t when it was made. However, she regularly rips off her arms or otherwise damages them and has to replace them with new ones. As such, her arms aren’t the original, presumably non-decaying ones.
Aw, very sweet
Actually, this makes me wonder a bit about Unity’s decay. If parts of her keep decaying, how has she kept the same face/head for so long?
Her main body doesn’t decay, as far as I know. It was treated so it wouldn’t when it was made. However, she regularly rips off her arms or otherwise damages them and has to replace them with new ones. As such, her arms aren’t the original, presumably non-decaying ones.
Warning: the above comment is 90% fan theory (the arm-ripping is a known fact), but supported by canon.
Judging by all the green patches when we see colored versions of her, I’d say her legs have the same problem.