Portable art (sometimes called mobiliary art) refers to the small examples of Prehistoric art that could be carried from place to place, which is especially characteristic of the Art of the Upper Palaeolithic and Mesolithic eras. Often made of ivory, bone, antlers or stone, these pieces have been found in South Africa all the way up to Eurasia. It is one of the two main categories of Prehistoric art, the other being the immobile Parietal art, effectively synonymous with rock art. Though the game hunted for food was a recurring subject within portable art, the over 10,000 pieces that have been discovered exhibit a great diversity in terms of scale, subject, use, date of creation, and media. Originally seen as less important than the cave paintings (see Lascaux, Chauvet, or Nawarla Gabarnmang) that also marked prehistoric art, portable art was thought to be merely preceding sketches or plans to be developed in later, larger parietal, or permanent, art. Over the years, however, the study of portable art has come into its own as archaeologists realize much information about prehistoric culture, livelihood, and societal structure can be gathered from these works or art. Categories of Portable Art Slightly Modified Natural Objects Usually composed of fossils, teeth, shells, and bone, slightly modified natural objects were pre-existing objects which prehistoric man altered by etching lines or patterns, drilling holes, or other simple techniques which changed the original object into a piece of artwork, typically jewellery. Engraved or Painted Stone As many as 1,000 sites with instances of decorated stone have been discovered. Sandstone, limestone, slate, or stalagmite were the most common types of material employed, and were usually adorned with animal figures or symbols. Such pieces have been interpreted by some archaeologists to be predecessors serving as sketches to a later, more developed cave painting. Engraved or Painted Bone Similar to engraved or painted stone works, the subjects of the bone pieces were typically game animals and symbols. Unlike their stone counterparts, however, decorated bone works are often much smaller in scale and are seen less frequently, as bone is much more difficult than stone to engrave. Carved Bone and Antler Most frequently used in the carving of spear-throwers, carved bone and antler pieces are significant because of the great amount of time, effort, and painstaking detail with which they were carved. As a result, a common belief among archaeologists is that such