From Guild Wars 2 Wiki
Experimental Ooze is a trophy required for the The Juggernaut III: The Colossus legendary weapon collection.“
Hint: Feed Experimental Remnant to your Tiny Chromatic Ooze. Rakkan offers this food for a reasonable price after defeating the Risen Broodmother in Cursed Shore.
— In-game description
- This item does not enter your inventory. It is added directly to the collection.