I have seen this related question - but it was about the almond peels and not their shells:
How do I recycle these? My relatives advised me to burn it all up, as it drives away mosquitoes. Others said to just bury it into the soil and it will compost itself away, but I doubt if this will ever happen (as these are hard shells). Powdering these shells came to my mind, but I don't know what to do with the powder either (and if my mixer grinder can sustain those hard shells in the first place).
The thing is that I have nearly a kilogram of these almond shells, so I want them to the best use. Thank you for your suggestions!