Can I sell the excess alien technologies?

Hold on to Zrbite and Aqua Plastic. They are required to construct a wide variety of items and will only get more important over the course of the game.

Ion Beam Accelerator and Magnetic Navigation are required for building alien technology submarines. But you only need 1 of them each for most subs (the best one requires two ion beam accelerators and one navigation). You are not going to build that many subs, you can build these components yourself if you need to and you will farm plenty more of these over the course of the game. So it might make sense to hoard a few of these if building subs is something you want to do in the near future, but it doesn't makes sense to hoard as many as you already got. If you have already researched them and are currently satisfied with your tritons and barracudas, you might want to consider to get rid of them all.

The following items are research-only items. You can sell all but one if you haven't researched them yet. When they are researched, you can sell them all:

• Alien Cryogenics
• Alien Cloning
• Alien Learning Arrays
• Alien Implanter
• Alien Sub Construction
• Examination Room
• Alien Re-animation Zone
• Any Alien Corpses