Teleporter Pyramids are a set of tools in Divinity: Original Sin 2.
"Glowing runes mark this pyramid as an item far out of the ordinary. Using it will teleport the wielder to the location of a near-identical pyramid."
There are four pyramids in total, the first two of which can be obtained after act 1. When you select one of the pyramids, it will give you the option to teleport to one of its differently coloured counterparts, once they have been obtained.
It is worth noting that the usage of the pyramids is blocked from The Lady Vengeance upon arrival to Reaper's Coast