From Defiance Wiki
An Ark Spike is a type of Spike.
An Ark Hunter discovered Dark Matter taking over a large Arkfall, defeated them and then downloaded the access codes for the Ark nav systems. The ark hunter scavenged a comm unit and some concentrated Gulanite crystals to construct the spike. An Ark Brain Interface was used to complete it and a signal repeater was placed on the Golden Gate Bridge to amplify the signal and control ark pieces. (Main Mission:New Discoveries, Main Mission:Drawing a Map, Main Mission:Dark Crystals, Main Mission:In Enemy Territory, Main Mission:Nowhere To Go But Up)