Cracked Silithid Carapace

This item begins the quest Parts of the Swarm, but may require one or more of the quests from the The Swarm Grows quests in order to drop.

Source
This item drops from Silithid Searchers, Silithid Hive Drones, and Silithid Invaders at the Rustmaul Digsite in the Shimmering Flats, Thousand Needles. If you are eligible for the drop, it will drop from the first Silithid you kill here.