In the mummification process in ancient Egypt, the nostrils of the deceased were usually stuffed with a material called resin-soaked linen. This was done to prevent decomposition and maintain the shape of the nose during the mummification process. To find this information, you can refer to reliable sources such as books on Egyptian civilization, scientific articles, or websites of reputable archaeological institutions like the British Museum or the Metropolitan Museum of Art. Such sources often provide detailed explanations of the mummification process, including the materials used.