It was a common source of grit additive for making mortar (the wet sloppy stuff, not the ordnance!) but I think that's largely a thing of the past now. Shell-grit mortar was common in early colonial construction in Australia, for example.
'Wicked-pedia' also state -
"Shell grit is coarsely ground or broken seashells. It is used, among other things, by birds as a source of calcium for egg shell production, and to aid digestion.
Other uses include protecting plants from slugs or snails[1] and in aquariums."
Mike
|