Flickr user Waffle Whiffer has posted a set of trading cards given out at Cleveland area McDonald's restaurants in 1974, each featuring a McDonaldland character visiting a prominent local attraction. The Cleveland Museum of Natural History was lucky enough to snare Grimace for its card. Who knew the lovable purple blob was such a natural history lover?
On the image's description, the Whiffer writes, "Note that he's referred to as *The* Grimace here, less than a year after his transformation from the four-armed 'Evil Grimace'." This is, I'm delighted to report, not a joke. When Grimace was introduced, he was indeed a four-armed ne'er-do-well. You can learn more about him here. Menacing, though less so than Mortal Kombat's Goro, who he almost certainly inspired.
Speculation abounds as to Grimace's true nature, but I have my own pet theory. Dude's a bryozoan.