Toggle made of a petrified tooth of a Hypercoryphodon. The Hypercoryphodon is an extinct genus of hippopotamus-like herbivores that roamed the wetlands of Mongolia some 45 million years ago. The carver has used this tooth to create a toggle in the shape of a cicada by scratching the sides of the tooth to make them look like wings. A cicada symbolizes Immortality. It is hard to date the time of manufacture of this toggle but its smooth edges denote a period of use which is long enough to place it in the Qing period (1644 – 1912). Length 5.8 cm. Width2.9 cm. Depth 2.7 cm.