Who is Master?

Or not. When I first read the bottom of this bottle I thought it said "Gravy is Master," but on closer look I think the "is" is actually a "15." Seems I don't know what is is.

But I do know where Dead Horse Bay is, since I went there for the first time today, led by a trustworthy Bay Master. There were no Dead Horses there, just a dead horseshoe crab. I also saw a rat's tail sans rat lying among some kind of dark brown curled pods under a leafless tree, some kind of root that looked like an enormous rat's tailed interwoven with a chunk of rusted metal, and bottles, bottles bottles... bottles in tide pools, bottles on sand, bottles in pieces, bottles covered with algae, some bottles for which the reuse was or is forbidden by federal law, so should I abstain from threading a flower into that Cointreau bottle, even a single bachelor's button?
I've never ever used Gravy Master. Like Bacos, It's a completely vegetarian product, as per this blurb I found at the Yankee Grocery: Gravy Master: A 5.0 fluid ounce bottle of a concentrated blend of spices and caramel color, blended to enhance the natural flavors and appearance of gravies, vegetables, meats, fish, poultry. Gravy Master is perfect for vegetarians, as it contains NO MEAT and is certified KosherGravy Master, parve, certified Kosher. Gravy Master in its unique glass bottle, has been on New England pantry shelves since 1935.

I guess I'm in the mood for gravy. Gravy for everyone!