Here's a bit more detail:
* Limestone: This type of sedimentary rock forms from the accumulation of marine organisms' shells and other calcium carbonate materials.
* Formation: Over millions of years, layers of limestone were deposited, forming cliffs along the coast. These cliffs were then eroded by wind and waves, creating caves. The caves eventually collapsed, leaving behind the iconic stacks known as the Twelve Apostles.
So, the Twelve Apostles are not made of granite, sandstone, or other rock types, but rather from limestone, a rock formed from the remnants of marine life!