The French name for the item gives you a better idea what's up with them: Memoquartz.

Using quartz crystal as a storage medium has been a concept in science fiction for a long time, but it actually is possible to laser-etch crystal and keep the information for millions of years without degradation. The thing is, our current techniques don't allow you to fit all that much data on one. That would go a long way to explaining why there are so many and why they vary so much, but so might the idea that the Allag just really liked using them while they had them. Think about how many discs you've had laying around over the past decade. I had a few hundred just in AOL trial disks.