Bricks are an inexpensive building block in a game that is used for many structures like brick houses or ash block buildings. Durability doubles when anchored on a planet as described in the description.
It can only be crafted using an Assembler as it has water (a fluid) in its crafting recipe.
In-game description
"A cheap material made from baked clay useful for building houses. Its durability doubles when anchored on a planet."