What began as a burger alternative has morphed into a bona fide cultural obsession. Introduced in 1981, McDonald's McRib sandwich didn't always have the rabid following it boasts today. With the announcement of its return after another year of retirement, here are 10 things that you might not have known about the Halley's Comet of fast food menu items.

1. THE SANDWICH CONTAINS 70 INGREDIENTS.

There’s more to a McRib than barbecue sauce-slathered pork on a bun with onions and pickles. The sandwich contains a staggering 70 different ingredients, the least innocuous of which are “pig bits like tripe, heart, and scalded stomach.” Add in some azodicarbonamide, ammonium sulfate, ethoxylated mono- and diglycerides and … well, you get the idea.

2. KANGAROO MEAT IS NOT ONE OF THE INGREDIENTS.

A persistent urban legend lingering around the internet says the rib-shaped patty is actually made of Australia’s famous roos. (It’s not.)

3. IT HAS BEEN AROUND FOR MORE THAN 35 YEARS.

The McRib debuted on McDonald’s menus in 1981, but it was far from an immediate hit. It was pulled from menus in 1985 because of poor sales. In 1994, the fast food behemoth tried again and found greater success with the McRib. In 2005, the sandwich became a bit more elusive, popping up for limited-time spans only. (To find the McRib nearest you, there's a McRib Locator.)

4. IT WAS INSPIRED BY A TRIP TO CHARLESTON, SOUTH CAROLINA.

Rene Arend, who served as McDonald's executive chef from 1976 to 2004, was inspired to create the McRib after consuming several pulled pork sandwiches during a trip to Charleston. He thought the flavor combination “should really go over.”

5. YOU CAN THANK CHICKEN FARMERS FOR THE MCRIB'S INVENTION.

Turns out McNuggets, which debuted in 1979, were so popular that McDonald’s couldn’t keep up with demand. As Arend told Maxim in 2009, “There wasn’t a system to supply enough chicken. We had to come up with something to give the other franchises as a new product. So the McRib came about because of the shortage of chickens.”

6. YOU CAN THANK THE FLINSTONES FOR ITS RETURN.

After mediocre sales, the McRib was pulled from the national menu in 1985. When the live-action The Flintstones movie hit theaters in 1994, McDonald’s capitalized on the resemblance between the slab o’ ribs atop the Flintmobile and the pork patty, and brought it back as a movie tie-in. Rosie O’Donnell was in the commercial, but John Goodman declined.

7. ITS SHAPE IS VERY INTENTIONAL.

The McRib is sort of famous for not containing ribs, so why does it look like a slab of ribs? Because, that’s why. “Some thought, why not just make it round?” recalls Arend. “It would’ve been easier. But I wanted it to look like a slab of ribs.” So there you have it.

8. IN 2011, MCDONALD'S HOSTED THE QUEST FOR THE GOLDEN MCRIB.

We don’t know exactly what this means, but it seems there were Golden McRibs “virtually hidden in McDonald’s across the country.” Previous McRib events: the “Legend of the McRib” contest, which asked fans to create a mythical history for the sandwich (perhaps this is where the kangaroo meat legend came from?) and three McRib Farewell Tours, in 2005, 2006 and 2007.

9. A (FAKE) PETITION TO SAVE THE MCRIB WAS FEATURED ON THE MCDONALD’S WEBSITE IN 2005.

It was sponsored by the Boneless Pig Farmers of America.

10. THE PROCESS OF TURNING MEAT INTO A MCRIB PATTY TAKES ABOUT 45 MINUTES.

"The pork meat is chopped up, then seasoned, then formed into that shape that looks like a rib back," Rob Cannell, former director of McDonald’s U.S. supply chain, told Maxim in 2009. "Then we flash-freeze it. The whole process from fresh pork to frozen McRib takes about 45 minutes.”

An earlier version of this article ran in 2011.