He is a deity who protects seeds and grain, particularly barley. Or is he? There appears to be a little confusion, perhaps due to over-zealous attempts to extract his personality from translations of his name. (It appears that ‘Simargl’ may mean ‘family’, ‘barley’, ‘harvest’ or ‘seven-headed purple aardvark’.)
We prefer our own eminently feasible theory that he was really two gods, Sim and Argl, who became inseparable drinking buddies after a night of hard gargling.
Other, more sensible, sources claim he is a dog with wings, or even a griffin. Which leads us to enquire why on earth such a griffin would spend its time protecting barley. What does barley needs protecting from? The world needs to be told.