blackpaint20:

Carved from ivory, this model shows a human male face on one side and a skull crawling with worms on the other. A banner with an inscription runs around the man’s face. This type of model is thought to be a memento mori – literally a reminder of death and the shortness of life. The skull was the symbol of death from the 1500s onwards. Previously death was represented as a skeleton accompanied by a living victim.