Sludge settles to the bottom, leaving clean water on top.

FORBES: Muckraker

However, a group of six divers inspected the bottom of the lake on Saturday and discovered no fragments amid the sludge.

BBC: Russia sends clean-up team to meteorite-hit Urals

Under the plate rack on the draining board and at the bottom of the plastic pot for the cutlery was a murky gray sludge.

NEWYORKER: Friendly Fire