Short version:
I possibly have an immortal echidna on my hands. Is there any way of knowing if this is a bug or an uber-lucky echidna?
Long version:
A minotaur showed up at my fort, but instead of going for my dwarfs, he decided to beat up an echidna nearby. He chased it and started beating the hell out of it near the map's edge. It lasted for some time, as minotaur striked and gored the echidna (quite long actually), before my squad of macedwarfs showed up from beneath the moutain.
One mace dwarf charged forward and killed of the minotaur in three strikes (neck->leg->brain). Being bored as hell with no decent enemies in my evil biome, I ordered the squad to kill the echidna. So they came one by one and started beating the poor creature with their maces. Then a mace lord came and invented echidna gold - punching it hard enough that it flies along the map border. Now 5 macedwarfs are beating the echidna with maces 24/7 but it still lives, is unconcious and has only one damaged part - upper body (red).
I checked the battle logs with the minotaur and with my macedwarfs. They all hit the echidna it its upper body, every time. The only time other bodyparts are involved is when it is propelled by the force of the blow, but then its get "the hair is teared" or something. It even doesn't show on the health status.
I wonder what happens next...