The hidden beach, box of mystery

Artwork for Environment challenge box of mystery!

This lost city appeared on this hidden beach with the power of the mysterious box that keeps the gate open to it.
The power of this box is controlled by the people of the city. They have the ability to travel with it through time looking for a safe place away from threats. In addition, the whole part changes round and created and the passage portal for them.
The box keeps their city safe with the energy bubble until they are sure of the place.