There are various possiblities to use your pyramids - as shown in your task bar (right hand side here). You can drop+use - use - drop.

As long as you have one pyramid safely somewhere outside and the other in your inventory you can teleport yourself out of dangerous/inaccessable areas by having the pyramid in your inventory - or dropping it and clicking on it to travel from pyramid A to pyramid B.

If you wish to pick it up again => drag&drop it into your inventory.