Gate Key

The Gate Key is a device that opens the Time Gates in Chrono Trigger. It was created by Lucca.

The Queen is Gone
After successfully rescuing both Queen Leene and Marle in 600 A.D., Crono and his party head back to the Time Gate in Truce Canyon. Lucca unveils her newest invention, the Gate Key, to open up the portal manually. Together, the three of them jump back to 1000 A.D.