"This inflatable Octorok organ has a lot of lift, so attach it to items you want to see float. Hold it in your hands, and then place it on an object to attach it."
The Octo Balloon is a material found in Breath of the Wild. They can be obtained by defeating Octorok of all variety, found all over Hyrule. This material can be used in combination with various Creatures to create different types of Elixirs, which increment Link's stats for a period of time, but can also be traded with Kilton, in his shop, the Fang and Bone, for just 1 Mon each.
A unique feature of the Octo Balloon is that if Link holds one and drops it on another item, such as a Crate, that item will begin to float in the air for a short period of time before the balloons pop, and the item falls to the ground.