The abalone shell is a traditional vessel in which Native American herbs and smudges can be burnt.
 
The shell is great for leaning burning sticks on while they burn and with the addition of sand or earth, they can be then used to help extinguish them afterward.
 
Loose herbs or the broken ends of smudge sticks can also be placed in the shell for burning, again with or without sand or earth.
 
Mini are 2-4", Small are 4-6", Large are 6-7". Size medium is shown in the photos.