Some kind of Lovecraftian horror.
An amorphous black mass of building materials,
Car parts, and bodies,
Flowing towards you just faster than you can run,
Bound to engulf you.
The unknown consumer of the familiar,
Family, friends, and memories.
You won't drown,
You will be ground and crushed into something
Unrecognizable,
Reconstituted into the mass.
It flows uncontested until some sick consciousness
Rears it back. Placidly it is absorbed
Into the Earth where it waits beyond the imaginations
Of those whose lives have been spared.
Hibernating until it is summoned or unleashed.
