There's a bunch of gems from when lightning strikes. I've accidentally duplicated them a few times moving a lot to different locations, putting everything grabbable into someone's inventory first before deleteing the old lot and moving them to the new copy lot.
(I know grabbable is not a real word, but it is now because I say so!)
There's also rewards and rare items you can get from the Astronaut career. Probably from the Scientist career too.
I'll make a list and post it here or what I have in-game for focusing items, when I get a round tuit. I mean, around to it.
