Treasure Bags are small purple bags which randomly drop from enemies when they die. When a Treasure Bag drops, all members in a group are able to pick up the same bag. A Treasure Bag disappears from your sight once you pick it up, but other group members who haven't picked it up yet can still see it and pick it up for themselves.
A Treasure Bag vanishes from sight after 10 minutes if you don't pick it up.
In regular quests, Treasure Bags contain Collectables which can be turned in for consumables and augments across Stormreach through Collector NPCs. These Collectors are indicated on city maps as blue circles grouped as a triangle. Items from Treasure Bags are also used in Cannith Crafting, and as such, can be valued by players and sold in the Auction House for inflated amounts.