Other varieties of poppers include the stovetop popper with a turn crank connected to a spindle and blade that can be manually circulated around the bottom base of the popper pan. The rotation of the blade allows the kernels to be moved within the popper so the heat is distributed around the kernel to pop it more effectively and without leaving many kernels unpopped. Popcorn poppers that are made to be held over open fires consist of some type of a formed metal mesh or flat metal that may be round, oval-shaped, square, or rectangular for use when camping or on picnics where open pit fires are most common. This type of popper has been used since early times when popcorn was first discovered as ears of corn were thrown into a hot fire. The popcorn popper was then developed to be held over fires made for cooking in the homes of early settlers and the basic concept remains very much the same as was created for popping corn during those times.