This Article Contains information directly from the Pikmin Games. This article is based off of an Enemy/Treasure/Area/Cave/Pikmin/Character from the Pikmin series of Games.
The Decorative Goo is a tube of blue "Mario Paint", (referencing the Nintendo character, Mario's, Super Nintendo title: Mario Paint). It is apparently used and is bent. It is found in the Awakening Wood and right near the original location of the blue Onion. It can be easily achieved once you obtain ten Blue Pikmin. This is also where the Radiation Canopy was found in Pikmin 1. When viewed in the Treasure Hoard, the dried blue paint under it is missing, and the tube of paint is floating.