Any surfaces that slowly sink anything on them deeper and deeper until finally suffocating them, though not necessarily lethal if too shallow. This is applicable regardless if it's sand or not, as long as it behaves the same. Not for realistic quicks
The first video game about Quicksand was released on June 1, 1991.
Note that quicksand and similar as seen in fiction, video games, and such do NOT behave like real quicksand. So this is NOT for realistic depiction of quicksand.
Real quicksand is practically just muddy water with the surface overlayed with fine sand on the top that makes it look like safe to pass plain sand but is in reality a (deep) pool of water. The surprise causing most problems, and the murkyness and muddyness makes getting out not as easy, as well as locating actual edge of the potholes.
Dry quicksand - which is essentially much closer to the fictional depictions - has been demonstrated in laboratory experiments, but not yet found in nature.