The hairy frog is also notable in possessing retractable "claws", which it may project through the skin, apparently by intentionally breaking the bones of the toe.[5] These are not true claws, as they are made of bone, not keratin. In addition, there is a small bony nodule nestled in the tissue just beyond the frog's fingertip. When sheathed, each claw is anchored to the nodule with tough strands of collagen. When the frog is grabbed or attacked, it breaks the nodule connection and forces the sharpened bones through the skin.[6][7] Although a retraction mechanism is not known, it has been hypothesized that the claws later retract passively, while the damaged tissue is regenerated.

This type of natural weaponry appears to be unique in the animal kingdom, although the Otton frog possesses a similar "spike" in its thumb.[8] An alternative hypothesis is that the broken bones could provide a better grip on rocks.[9]

https://en.wikipedia.org/wiki/Hairy_frog

Yep, pretty horrifying, accurate name.