It looks like a brass 1-piece button. If it's a button, your find might be a Livery button. Is it a 1-piece or 2-piece button?
Unfortunately, since modernday clothing-manufacturers like to put fancy-looking metal buttons on expensive jackets and coats, your button might be a modern "Fashion" button. If it's a brass 1-piece button, it's more likely to be a genuinely old button.
For anybody here who doesn't already know:
Livery buttons date from "about" the 1700s on through the present, though they've been out-of-favor for a long time. Most are from the 1800s through early-1900s. They were for the uniforms of the household servants of wealthy people, such as butlers, housemaids, and coachmen. Livery buttons usually showed the "Family Crest" of the wealthy person. I'll include photos of a couple of example of Livery buttons.
I don't think the animal on it is a lion. The tail is much too long, as it the beastie's tongue. It seems to be one of the mythical critters seen on Livery buttons, such as a Griffin... but it's not a Griffin.
