Concept: Goyer's Giant
"When finally the source of the cacophony was located, our plight turned from miserable to catastrophic. We had located one of the 'colossi' the guides had been so anxious to avoid.
It stood on six muscular legs, easily 15 meters tall and nearly as wide. It was situated in one of the main caverns where the heat was not so suffocating. Four enormous, eyeless heads writhed purposefully at the end of tortured, misshapen necks, and blisters filled with some sort of greenish phosphor bulged sickly from most of its thin, vein-riddled flesh, with the odd one burst and dripping the viscous fluid onto the rocks, where it hissed and evaporated. Wriggling cilia coated the beast's undercarriage, radiating massive heat that we could feel even at the other side of the cave. Lithe, bony, rib-like protrusions on its sides appeared at first to be static, but as we watched one of its heads homed in on a small flock of the large bats we had encountered in the cave mouth (see pg. 57); to our amazement the concealed lower end of this 'rib' wrenched free and its barbed tip flashed outward with a speed we hadn't expected. A bat was speared and, shrieking horribly, stuffed into the multi-hinged jaw of the attendant head.
From a scientific standpoint I wanted to further observe the creature, but [our sole remaining guide] Orthos insisted we move on before the giant caught our scent. Remembering the uncanny speed of the bat's demise, I didn't argue."
-excerpted from page 127 of the expedition journal of naturalist Stanislaus Goyer; charred partial pages recovered in the Cueva del Milodón cave system in Chile after his exploration party disappeared, August 1906.
"You may have noticed my brain is no longer pristine." - Spider Jerusalem