The brick is an inexpensive building block for structures like brick houses or ash block buildings. Durability doubles when anchored on a planet as described in the description. This item is primarily ornamental, though it can also serve as a cheap form of shielding against enemy players. 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."