Sculpture is an inherently tangible form of art, dealing with real, 3-dimensional objects. Sculptures are often representational but can be abstract as well, and range in size from hand-holdable to mountan-sized. Both shape (dictated by the sculptor) and surface appearance (often arising from the physical material as much as from explicit control by the sculptor) are important in the appearance of the sculpture. Material is also important because those used for sculptures are commonly durable enough to survive in the same form for centuries or millennia, meaning that sculptures are some of the longest-lasting artistic artifacts yet produced by human civilization.