(NEXSTAR) – Twitter users who follow the official McDonald’s account were greeted to a nostalgic sight on Monday: the large purple face of Grimace — bug-eyed and nearly expressionless — staring directly back at them.

McDonald’s ultimately revealed that Grimace is back to promote its upcoming “Grimace Birthday Meal,” which comes complete with a brand-new (and very purple) berry-vanilla shake.

There’s just one thing McDonald’s declined to fully explain: Just what the heck are we looking at, here?

Grimace, by McDonald’s own admission, is an “ambiguous” blob of a mascot. Introduced in 1971 as “Evil Grimace,” the character was first depicted as a villain — with four arms — who was singularly focused on stealing McDonald’s milkshakes, as seen in early TV commercials.

Over the years, Grimace eventually lost his mad lust for milkshakes (and two of his arms) and became best buds with Ronald McDonald.

But Grimace was always a bit different from his fellow McDonald’s mascots. Ronald McDonald, for instance, is clearly a clown. The Hamburglar is some kind of humanoid burger thief. And Mayor McCheese, as his name suggests, is the cheeseburger-headed mayor of McDonaldland.

Grimace, though, is more of a mystery to the casual observer.

Grimace apparently resides in Malibu, stands at 9 feet tall, and is legally permitted to operate a vehicle in California, according to a photo provided by McDonald’s. (McDonald’s)

Nearly a decade ago, however, the team behind the McDonald’s Twitter account basically revealed what Grimace actually is. During a 2014 exchange, the company responded to a question about the character, confirming that Grimace was either “the embodiment of a milkshake or taste bud.”

Brian Bates, an award-winning McDonald’s manager from Canada, seemed to be under the impression that the latter was true in a 2021 interview with the Canadian Broadcasting Corporation, confidently asserting that Grimace is essentially a huge anthropomorphic taste bud.

“He is an enormous taste bud, but a taste bud nonetheless,” Bates told the outlet.

After Bates casually dropped that nugget of knowledge, social media started sounding off with their shocked and sometimes horrified reactions.

“Ever since I learned that Grimace is a taste bud I have not known peace,” one Twitter user wrote.

“If grimace is a taste bud, then your mouth is a metropolis for all grimace kind,” another theorized.

Despite the company’s earlier admissions, a spokesperson for McDonald’s declined to comment on Grimace’s corporeal form on Tuesday morning. And in its latest press release, McDonald’s further suggested that “we’ll never know” what Grimace actually is.

“Grimace is from Grimace Island and comes from a huge family (including his Grandma Winky, aunts Millie and Tillie and his Uncle O’Grimacey!)” wrote McDonald’s in the release, apparently hoping to satisfy any questions with a detailed description of Grimace’s lineage. “Our timeless bestie has become a fan-favorite known for his signature fuzzy purple look, friendly and playful personality, love for shakes, and of course – ambiguous nature.”

The Grimace Birthday Meal is available for a limited time beginning June 12, according to McDonald’s.