What was the 3rd house made of in "The Three Little Pigs" fable?

"The Three Little Pigs" is a fable about three pigs that build their houses of different materials. A Big Bad Wolf blows down the first two pigs' houses, which are made of straw and sticks, respectively, but can't destroy the third pig's house, which is made of bricks. The printed versions of this fable date back to the 1840s, but the story is thought to be much older.

Source: Wikipedia