This is going to be a short guide since it's not that complicated.
Xen grenades are very useful because any time you find them, they spawn infinitely.



However, the game doesn't exactly explain how to get them, only to squeeze them/hit a button to prime them. And there are a number of videos out there that are flat-out incorrect. They all say to swipe at the grenade and grab it quickly. Sure, this works maybe 25% of the time, but anytime it doesn't you have to wait for the grenade stalk to open up to you again.

This method is pretty much flawless.

Step 1: Put one hand on the lower 'belly' part of it. I use my right hand to do this. It doesn't particularly matter. Rub or tickle it if it makes you feel better.

After that, usually the top opens up as shown.


I'm not sure if it does this all the time because I'm usually not looking at it at this point and I instinctively just grab it with my other hand.

But in any case, grabbing the grenade at this point should be a piece of cake.


Now go forth and spam Xen grenades!