One can find the fastest-growing animal cells in nature in moose antlers—the bone cells that make up the 6 feet (1.8 m) wide on average antlers of male moose allow them to shed and entirely regrow the large antlers each year. The main purpose of moose antlers is as a weapon for fighting for a mate, a period that generally only lasts from September to October. Therefore, antlers are unneeded after that point. The growth is prompted by the release of hormones that occurs around April or May, and each new set of antlers is generally increasingly larger than the last as a moose reaches its prime at around six years. After that, the cells in the antlers decrease in growth speed until the antlers eventually recede.
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