From The LNR Book of Knowledge

Symbiosis

Rewards: Caller of Storms (CL55, Fencer:Master)

Start: Bag (“Inspect”), [1328,-2508], Mining Fields, Mustafar

Part 1: A virus? - Examine the dead Treasure Hunter corpses in the immediate area; Radial menu: “Examine corpse”; Combat: Spawns 2 Unknown Arachnoids (CL67) each time; On one of the corpses you’ll get the next part of the quest

Part 2: Dangerous indeed - Grab the contents of the Bag [1328,-2508]; Radial menu: “Seal and grab container”

Part 3: Stop the plague - Lava river [1296,-2275]; Travel to the waypoint and you will throw the bag into the lava

Part 4: Looking for clues - Corpses [1335,-2516]; Examine the dead Treasure Hunter corpse up on the hill [1346,-2565]; Radial menu: “Examine corpse”

Part 5: All you can do - Combat: After the second popup message you get the reward and 6 Unknown Arachnoids (CL67) will spawn, you don’t have to fight them though