Shell grit is coarsely ground or broken

seashells A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washe ...

. It is used, among other things, by birds as a source of calcium for

egg shell An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats. Diversity Worm eggs Nematode eggs present a two layered structure: an external vitellin layer made of chitin that confers mechanical ...

production, and to aid

digestion Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...

. Other uses include protecting plants from slugs or snailsSnails, Shell grit & Liliums - Gardening in Oz Forum - GardenWeb
and for aquariums.

References

External links

* http://ozbird.com/roleofgrit.htm A discussion on the role of grit in a bird's diet. * http://www.birdhealth.com.au/bird/budgie/feeding.html A discussion on feeding Budgies, including the role of grit. Pedology {{soil-sci-stub