Incomplete evolutions

Add some armour (which would work like the Battlesuit armour) to chrysalises, and if the armour is broken, have an underdeveloped alien emerge: it should have less maximum health than usual, but able to fight or flee right away if necessary. If your chrysalis is broken, you don’t pay the full price of the evolution, but you’ll not get any discount compared to the original class you tried to evolve from for further evolutions.