Hidden Temple Altars are pieces of furniture that can be used for storage (and decoration). They can be crafted in your Crafting Menu (opened by "Q" as the default key) or at Crafting Tables (that still exist in older worlds), but only after the crafting-recipe has been unlocked by buying either the Hidden Temple Accessory Pack or the Hidden Temple Super Bundle in the Store. To craft 1 Hidden Temple Altar, you'll need (as of R32 in June 2016): When buying either (or both) of the temple bundles, you will also receive a few blocks each of Tourmaline and Wildwood as additional gifts.