Sci-Fi Star Crab STL

Space travellers have often pondered what miracle or misadventure of technology was the origin of the omnipresent spacecrab. Neither is their purpose entirely clear, nor their reason for rapid proliferation. They're often encountered slowly scuttling through salvage sites or mining operations and scrounging on bits of scrap, although their tastes appear indiscriminate.   Need a random NPC for your tabletop game that bumbles around with no purpose? The starcrab is somewhere between a stationary rock and an aimless critter. Like the wings of a butterfly this seemingly pointless robotic mishap could foil the targeting of a railgun and swing the tide of battle.