The earliest known Filipino art are the rock arts, where the oldest is the Angono Petroglyphs, made during the Neolithic age, dated between 6000 and 2000 BC. The carvings were possibly used as part of an ancient healing practice for sick children. This was followed by the Alab Petroglyphs, dated not later than 1500 BC, which exhibited symbols of fertility such as a pudenda. The art rock arts are petrographs, including the charcoal rock art from Peñablanca, charcoal rock art from Singnapan, red hematite art at Anda, and the recently discovered rock art from Monreal (Ticao), depicting monkeys, human faces, worms or snakes, plants, dragonflies, and birds. Between 890 and 710 BC, the Manunggul Jar was made in southern Palawan. It served as a secondary burial jar, where the top cover depicts the journey of the soul into the afterlife through a boat with a psychopomp. In 100 BC, the Kabayan Mummy Burial Caves were carved from a mountain. Between 5 BC-225 AD, the Maitum anthropomorphic pottery were created in Cotabato. The crafts were secondary burial jars, with many depicting human heads, hands, feet, and breast.