Time Crystal
From The Blockheads Wiki
Time crystals are used for a number of things: upgrading portals, warping in resources, warping in Blockheads, and speeding up crafting. They can be found in caves, or you can pay for them. The counter for how many time crystals you have should be visible in the upper right corner.
Notes
Time crystals are tied to the player/device, not to specific worlds. If you change from one world to another, your supply of time crystals moves stays with you.