I have found those in my tanks that I bought used with Eco Complete. I figured it was some fertilizer additive the previous owner had used. Are you thinking they are a living thing?
Well, did you put any root medic near the vesuvius??I use rootmedit root tabs (just started them).
Also some Flourish that i'm using while I'm waiting for my 'real' ferts to come in the mail.
I haven't added osmocote, and this tank was started from scratch using 100% Flourite. I really did rinse the plants well so I'd be surprised if so many little white balls escaped my attention - there are at least 10 visible not included the 3 that I removed to check them out!