The pods – which got their name Sarco as an abbreviation for sarcophagus – are portable devices that can be operated by users from the inside and work by reducing internal oxygen levels.

Source: https://www.dailymail.co.uk/sciencetech/article-12413791/Inventor-dubbed-Dr-Death-says-controversial-3D-printed-coffin-like-suicide-capsules-used-time-YEAR-pro-life-groups-warn-contraption-glamorizes-suicide.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

The sarcophagus lid was looted from the Abusir necropolis south of Cairo then transported to the US in 2008, eventually making its way to the Houston Museum of Natural Science in 2013, according to state media.

Source: https://www.al-monitor.com/originals/2023/01/egypt-recovers-2700-year-old-sarcophagus-lid-us

Using Desolate Dive/Descending Dark on the grave will open a secret passage underground, and players will need to travel to the right until finding a sarcophagus where Soul Eater is tucked away.

Source: https://gamerant.com/hollow-knight-charms-locations-where-find/