The dunes on Saturn's moon Titan, the largest moon in the Solar System, are composed primarily of organic sand grains. These sand grains are rich in carbon, hydrogen, oxygen, and nitrogen, which are the basic building blocks of life. The dunes are thought to be formed from the erosion and transport of this organic material by winds on Titan.

While the dunes are not directly made of comet dust, it is possible that some cometary material may be present within them. Comets are icy bodies that are made up of a mixture of ice and organic compounds, and they are thought to be the source of much of the organic material on Titan. It is therefore possible that some of the organic material in Titan's dunes may have been derived from comets, although this has not been definitively proven.