Petrified Oak Slab
Petrified Oak Slabs also known as "Alpha Slabs" or "Wooden Slabs" are a type of slab that utilizes the oak wood texture but has stone like properties and is an artifact from when all types of slab shared a single identifier. Before 1.13 and "The Flattening" many blocks shared identifiers and when slabs were being developed there was a single identifier for all slab types meaning they needed to all use a single material due to restrictions at the time, since all slabs before the wooden slab as it was then called were made of different variants of stone all slabs were assigned the stone material. When the other wood types of slabs were added they used a new identifier that allowed the wood slabs to use the wood material rather than stone, however due to fear of the old wooden slabs being burned due to them becoming flammable it was decided to keep the old stone variant of the oak slab. Once 1.13 released it was decided to keep this slab despite being uncraftable for many years and was given the new name of "Petrified Oak Slab".