You buy one and use it for decoration. No two are alike. The terra-cotta chimeneas are usually painted with an earthenware finish, rather than glazed, which means it holds up without chipping or peeling from the heat. Many are embossed with flowers, suns or other designs. Miniature versions are used for burning candles or incense.
Some people even use the big ones for that purpose.
Keep your wood fires low. If your chimenea is hot to the touch, then the fire is too hot. If sparks are coming out the top, it s beyond too hot. And never toss water on the flames to cool it down the water will cause the terra-cotta to crack. Cracking, in fact, is the bane of chimenea owners.