WTW for a tiny, preferably cylindrical, container?

So for context I'm writing a fantasy novel, and there's this small vessel characters can use to both store and release magic spells. To activate it, they would need to say "release" followed by thhe spell's name (e.g. Release, Fireball!) then throw the vessel towards the intended target, or at least the general direction of it. It is small enough in shape that you can hold it with only two fingers. Anyways, for now I call it "spell canisters" but it being a "canister" doesn't sit right with me. "Vial" and "flask" are already taken, nevertheless it still doesn't seem right, since the thing's typically not made out of glass. And it certainly isn't a "potion" lol. Anybody knows another word for it?