if something is a sink of something else then that something else corrosive from that something
things is not heavier_than_water_sink. spoil is plundering. hijacking is unnatural_thing. sack is not plundering. things is heavier_than_water_sink. sack is plundering. spoil is not plundering. sink is tangible_thing. sink is not tangible_thing. sink is not container_product.