I can confirm this bug has been happening quite a bit lately.
The only solution I have found is for an admin to use the \'/despawn_all\' command, but this only works if you know the ships name (needed for the command line).
The \'/destroy_entity\' command does not work because these ghost ships do not appear in the nav list, nor as triangles on the hud, nor do they have a diamond around the core, so you cannot select them to destroy them. They do however have a dot in the small radar window in the top right corner.
I notice a large spike in server and client load when you go near one of them. I drop to around 5fps when near one (usually ~400fps). Worse if you fly a big ship through one.
I\'ve seen it happen to turrets, ships and even just a bare cores. Both after they have been used, or even as they are created (x for a core, or a catalog ship). Our online server currently has one at spawn (2,2,2) right beside the shop, and I\'ve been unable to remove it as I have no idea who created it, or it\'s name.