Also see Withus Warp.
It is built in a + shape with five blocks. The outer blocks are end stone and the center block is an emerald block.
When built, the endstone will turn into smaller, 8x8-pixel blocks (much like mob heads) attached to the sides of the emerald block, which becomes an animated, pulsating rainbow crystal block.
Simply right-click the emerald block to be transported to the Celestis. Once the Configuration is used, a corresponding one will spawn in the Celestis. This is what the player spawns on.
Mining any of the transformed blocks of a Celestis Configuration will drop the original block and revert the other blocks to their original state.