Planked Wall

Underground cabins are lined with it, and unlike almost every other wall the world generates, you can knock it down and keep what falls. That is usually quicker than crafting a batch, and it turns an exploring trip into a materials run if you are building anything rustic.

Short of shimmer, there is no way to break it back into what it was made from. The likely reason is that it takes two ingredients and there is no block sharing its name to return them to. Craft what you need for the job rather than converting a stack on spec.