Axolotls can regenerate parts of their own brain and heart.
Why it is true
Unlike most vertebrates, these Mexican amphibians can rebuild complex brain and heart tissue without scarring, restoring full organ function.
Source: Regenerative Biology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.