They look like white little white boxes of bullets (didn't have time to texture them during the jam), after the first attack you find a few boxes after passing the steam pipe in the office to the right :) Hope that helps, if you have any further questions a walkthrough can be found here Walkthrough - DESCENT by ChristophGray (itch.io)
I'm going to pin this to the about section just in case people miss it as there have been multiple logs since then.