The Unknown Meteor is the rarest meteor in the mod. This is mostly due to the wealth of resources it provides. It may seem small at first, but it holds so much more to be seen. The shell of the meteor is comprised of ores from the main three meteors (Meteorite, Frezarite, and Kreknorite). On the center edges, there are glowstone blocks. The real amazing part is in the center. In the center of the meteor holds a chest which holds various rare (and some common) items. You can get any thing from Meteorite Armor to Diamonds!
Note that when blocked by a meteor shield, it still has a chance to give one or two items from its chest.