Some slabs break slower than their base blocks. These blocks are:

• Sandstone
• Cut Sandstone
• Red Sandstone
• Cut Red Sandstone
• Quartz Block

How to reproduce:

1. Obtain the aforementioned blocks in large quantities and make some of them into slabs.
2. Place them down.
3. Try to break them with a wooden pickaxe.
4. Find out that slabs break slower.