Dry quicksand
Dry quicksand is loose sand whose bulk density is reduced by blowing air through it and which yields easily to weight or pressure. It acts similarly to normal quicksand, but it does not contain any water and does not operate on the same principle. Dry quicksand is an example of a granular material. Historically, the existence of dry quicksand was doubted, and the reports of humans and complete caravans being lost in dry quicksand were considered to be folklore. In 2004, it was created in the laboratory, but it is still not clear what its actual prevalence in  nature is. Scientific research. Writing in "Nature", physicist Detlef Lohse and coworkers of University of Twente in Enschede, Netherlands allowed air to flow through very fine sand (typical grain diameter was about 40 micrometers) in a container with a perforated base. They then turned the air stream off before the start of the experiment and allowed the sand to settle: the packing fraction of this sand was only 41% (compared to 55–60% for untreated sand). Lohse found that a weighted table tennis ball (radius 2 cm, mass 133 g), when released from just above the surface of the sand, would  sink to about five diameters. Lohse also observed a "straight jet of sand [shooting] violently into the air after about 100 ms". Objects are known to make a splash when they hit sand, but this type of jet had never been described before. Lohse concluded that During the planning of the Project Apollo moon missions, dry quicksand on the moon was considered as a potential danger to the missions. The successful landings of the unmanned Surveyor probes a few years earlier and their observations of a solid, rocky surface largely discounted this possibility, however. The large plates at the end  of legs of the Apollo Lunar Module were designed to reduce this danger, but the astronauts did not encounter dry quicksand. In popular culture. In "Indiana Jones and the Kingdom of the Crystal Skull" Jones and Marion end up stuck in a dry sandpit. In "Miss Fisher and the Crypt of Tears", Phryne Fisher begins to sink in the Palestinian desert and calls out that she is sinking in quicksand. With no water nearby, it is likely meant to be dry quicksand. In "Lawrence of Arabia", T. E. Lawrence's servant Daud dies when falling into quicksand in the desert . In that scene, there is no evidence of water. In "The Princess Bride", Buttercup falls into dry quicksand, and Westley jumps in to save her. In Hotel Del Luna's episode 3, Jang Man Wol falls into dry quicksand.