Netsuke are miniature sculptures (around an Inch tall) that were invented in 17th-century Japan to serve a practical function (the two Japanese characters ne+tsuke mean "root" and "to attach").

Traditional Japanese garments—robes called Kosode and kimono—had no pockets; however, men who wore them needed a place to store their personal belongings, such as pipes, tobacco, money, seals, or medicines.

Their solution was to place such objects in containers (called Sagemono) hung by cords from the robes' sashes (obi). The containers may have been pouches or small woven baskets, but the most popular were beautifully crafted boxes, which were held shut by Ojime, which were sliding beads on cords. Whatever the form of the container, the fastener that secured the cord at the top of the sash was a carved, button-like toggle called a Netsuke.

Netsuke are usually made from Ivory, Hard woods, Metal, boar tusk, rhinoceros horn and some unusual materials like Walrus tusk, Whale's tooth, hippopotamus tooth and Tagua nut.
(From Wikipedia)