Sejan pit

The Sejan pit is located a short way north away from Witch's house in the middle of the darker-spotted forest.

Upon climbing (or falling and rolling) down into the pit, a number of coloured pottery shards can be found alongside a buried sarcophagus that can be dug out. The coffin can be opened either with the help of a crowbar and Strength 6 or with the player's bare hands and Strength 10.

Inside, skeletal remains of a creature can be found. It seems to have four eye sockets (placed symmetrically in a circle), a scratch near the right one, and a large hole on top of the skull, seemingly from a blunt impact.

The cadaver wears a necklace that can be taken. While the pendant is made from a smooth golden-like material that shows no signs of corrosion, the silvery chain is covered in rust. The face of the pendant has three identical glassy gems arranged in a diagonal line.

Behind the scenes
There's currently nothing else to do around the sarcophagus, but there is a portion of writing inaccessible in-game that shows that there is a room underneath the coffin, tall enough to stand in. It's currently unknown if that will actually be possible in future versions or if it's to be cut.