This one is looking at becoming a full story

It was born beneath layers of hard rock and sediment, left stewing for a thousand years and, when the time had come for it to be birthed, the parents or creators of this hideous beast were nowhere to be found. Had they given rise to something beyond even their own, apparently high, hopes and dreams? They had built the machines, the monitors, to run for so long; had they also thought the world would last to greet it? It did not consider such things as it burrowed through its aged prison to the silt-encrusted surface. The only thought on its mind, the all-consuming desire that drove it beyond all else… Was hunger.

Through empty streets littered with hollowed out husks of once-proud architecture, past bent and broken lamps and signs scribbled over with unknown markings, its path took it beyond the city and out into the fields. Soot where there had once been grass, cracked ash in place of trees, the world was as black as the sky above, the scent of long-departed smoke thick in its nostrils. Upon two legs or four, it strode or skittered. The ground was often even, but sometimes it would slant, or peak and the creature would realize that it had been traveling up for so long that it had forgotten the texture of gravity.

Not that it knew what gravity was, of course. Or what to expect beyond the most basic facts that it could gather and analyze without ambiguity. It did not simply shoot off into the sky, so something was either pulling or pressing it down. This could be resisted, but not indefinitely. It had devised a system within which travel became easier, maintaining its four-legged passage over distance and reserving the two-legged gait for the rare instances when it found a need to hold something in one of its more dexterous pincers.