It is not yet clear what a Macrocosm is, however it appears to be some sort of space device/ship is put into a planet's orbit. The Red Crystal that half the Garde have and Glass Orbs which the other half have that are somehow linked to Macrocosms, it is said that the Compasses glow when a Macrocosm is in orbit and can be used to track a location. It can also be tracked on the glass orbs.
Crayton is unconvinced that there is a friendly Macrocosm still operational, suggesting a Loric origin, but speculates that the Mogadorians must have stolen one. However, it is speculation that one exists and it is more likely that Number Five has something to do with tracking Marina.
The Glass Orbs have been referred to as a Macrocosm.
Garde confirmed to have this item:
Five (Not Confirmed but highly likely due to the mogs being able to pinpoint locations when chests are opened)