Those things were always weird to me. Especially the one in the ship. With how the vein-cables look and are so exposed, it looks more like they weren't originally part of the ship.

And I'm curious what the temple one does. Does magic need a generator? Will the temple become a giant robot and punch out the Diamonds?

Let’s bring this to its inevitable conclusion, the gem temple is actually an old mech (like Lagann from Gurren Lagann) laying dormant. I bet the Crystal Gems used it in the last battle for Earth before Rose parked it there.

Think about it, the old Gem colony ship they went to when chasing Peridot could have been mistaken for an ancient stone temple. The Crystal Gem’s temple could have been a prototype of whatever the hand ship connects to.