Amalgams are kind of immortal - if you try to attack them, it spams a lot of weird red text at you and their HP gets all screwy. Subsequently, the skelebro amalgam would probably do the same thing.Undyne eventually ends up taking them in and looking out for them though, so things aren't totally miserable for the poor thing.Edit - A dub! Done entirely digitally, god I was tiredUndyne, Sans, Papyrus (c) Undertale: there are no skelebro amalgams in canon do not worry