Cagite

 is a resource found in Caves. It can be harvested with a Cagite Harvester

can also be found in ship wrecks.

Harvest Strategies
is extremely plentiful in Alien Towers. After defeating boss monsters in a room with a Loot Crate, place a harvester within range of a Cagite node. Upgrade the harvester to max and simply wait. Note: This will collect Cagite from nearby nodes that may be on other floors of the tower.