Golems: 'Living'

Called golems for want of a better term, they are animate constructions. The ‘living’ golems are built out of part inanimate, part biological material. The creator then, somehow, imbues the golem with a life force and soul of its own (though presumably also ‘borrowed’ from another being, just as the golem’s other parts are). They are living; breathing creatures with the same needs (food, drink, entertainment) as all other beings. Cutting one open reveals multiple moving, pulsing organs: some made of stone, or felt, or wood, or flesh. However, as they are constructed, not born, they do not seem to be evincing any need for or capability of dying.
Who is creating these creatures, and how they are doing it, is yet a complete mystery to the Institute. Though numerous attempts have been made to dissect or destroy the golems, all that has been learned is a little about their physiology, and nothing about their mortality.