in groups at a time at enemy ships or massed enemy formations. Non-disposable finely-crafted throwing spears made from bamboo weighted with sand known as sugob were also used. Sugob were mainly used for close-quarters combat and were only thrown when they could be retrieved. Metal-tipped blowgun-spears called sumpit (or sumpitan), used by various ethnic groups in the islands of the Philippines, Borneo, and Sulawesi, were generally made from hollowed bamboo. They used thick short darts dipped in the concentrated sap of Antiaris toxicaria which could cause lethal cardiac arrest. Desalination Bamboo can be used in water desalination. A bamboo filter is used to remove the salt from seawater. Musical instruments Indicator of climate change The Song dynasty (960–1279 AD) Chinese scientist and polymath Shen Kuo (1031–1095) used the evidence of underground petrified bamboo found in the dry northern climate of Yan'an, Shanbei region, Shaanxi province to support his geological theory of gradual climate change. Kitchenware and other usage Bamboo is frequently used for cooking utensils within many cultures, and is used in the manufacture of chopsticks. In modern times, some see bamboo tools as an eco-friendly alternative to other manufactured utensils. Bamboo is also used to make eating utensils such as chopsticks, trays, and tea scoops. Several manufacturers offer bamboo bicycles, surfboards, snowboards, and skateboards. Bamboo has traditionally been used to make a wide range of everyday utensils and cutting boards, particularly in Japan, where archaeological excavations have uncovered bamboo baskets dating to the Late Jōmon period (2000–1000 BC). Bamboo has a long history of use in Asian furniture. Chinese bamboo furniture is a distinct style based on a millennia-long tradition, and bamboo is also used for floors due to its high hardness. In culture Several Asian cultures, including that of the Andaman Islands, believe humanity emerged from a bamboo stem. China Bamboo's long life makes it a Chinese symbol of uprightness and an Indian symbol of friendship. The rarity of its blossoming has led to the flowers' being regarded as a sign of impending famine. This may be due to rats feeding upon the profusion of flowers, then multiplying and destroying a large part of the local food supply. The most recent flowering began in May 2006 (see Mautam). Various bamboo species bloom in this manner about every 28–60 years. In Chinese culture, the bamboo, plum blossom, orchid, and chrysanthemum (often known as méi lán zhú jú in Chinese)