Stalking down the halls, new creatures sought their prey. They differed from beasts already in the human building. They didn't seek fleshly pleasures or mates. They sought prey, sustenance, though in true Love Hotel fashion, their hunting methods were a perfect, if gruesome, fit. Though their large size afforded them an advantage here (each arthropod-like beast easily the size of a well-built grown man), they stuck to numbers to ensure an ample supply of prey.
They differed slightly in appearance: some had simple suction for mouths, made to slurp up liquid nourishment, while others had mandibles sharp and serrated for severing and crushing flesh and bone alike. All of them, however, bore strange tubes on their abdomens, whether ridged, barbed, or smooth but as thick as a man's fist. Their purposes were unknown, but would soon be made clear.
All that was needed was prey.