zergRush99
Basically a series giant wormhole, uses 'The Void' (The Dimension of the Weave..) as the space in between, Venata Fissures are normally able to have outside ships allowed through, both ways, but when matched with Remna and Covenant tech, it rejects any unidentified objects, incinerating the object as it would enter, tearing it apart into mere atoms, only Entity able to travel across the Void without allowance is Sidera, the Creator of the Void.
(They aren't round though, try jagged rips in space..)