Nether Bricks

Nether Bricks is an upcoming block that will be added to the Nether. The bricks appear to be used to generate bridge-like structures. It can be seen in the second picture that there may be 2 different types of Netherrack Brick, one being a similar color to Netherrack and the other a darker shade of brown (more like Soul Sand)

In pre 1.9 nether brick is a UNIQUE block and CANNOT be crafted by netherrack. This MAY change in the full 1.9 update

Occurrence
Nether bricks make up the majority of the Nether Ruins structure, forming walls and supporting pillars.