Terracotta

Hardened clay is a block with a blast resistance comparable to that of stone-based blocks. It serves no purpose but as a decorative building material and as a moderate blast-resistant material. Hardened clay can be obtained by smelting clay blocks.

Smelting
Hardened Clay is not crafted in a Crafting Table with like Clay and Stone

Behavior
Hardened clay has the same explosion resistance as most other stone blocks, which is significantly higher than the block of clay it's made from. A block of hardened clay one meter away from an explosion will protect any blocks behind it, though it will be destroyed in the process.

Hardened Clay makes a sound like Stone

Stained Clay
Stained clay, also known as stained hardened clay, is a colored variation of hardened clay. It is available in the same 16 colors that wool can be dyed, although the shading of the color is less vibrant. Nevertheless, stained clay is a beneficial alternative to colored wool, due to its smoother and softer texture when used in building structures, the fact that fire does not spread when struck by lightning or set on fire, as well as its greater blast resistance. Dyed clay cannot be recolored.

Trivia

 * Hardened clay was originally suggested by a YouTuber, BlameTC, to be similar to Native American Pueblos.
 * Stained clay has the same blast resistance as ordinary hardened clay.
 * Hardened clay placed against TNT will protect any block behind it from the explosion, but will be destroyed in the process.
 * Because hardened clay has a dark, tan base color, most of the dyed colors of stained clay has a slightly brownish mix to them.