Board Thread:Questions and Answers/@comment-3125355-20131216070133/@comment-1458758-20140406160743

Well the predator is typically something that have evolved to eat these creatures in their natural habitat, so whatever it is, especially as a non-sapient creature wouldn't necessarily be developed to eat through the armour.

Having said that, some sort of living sponge that absorbs radiation and uses it to grow would be cool.