M&Ms, in all their varied colors, have been occupying shelves on candy displays for decades. Like most treats, the chocolate confections with a hard candy shell bring with them a sense of familiarity. Consumers know exactly what they’re getting—blue, brown, yellow, orange, green, and red pieces.

But there is a dark period in M&Ms history. One in which that color line-up was disrupted for more than a decade. From 1976 to 1987, there were no red M&Ms.

The candy, which was introduced by the Mars company in 1941, succumbed to a brief bout of hysteria in 1976, when federal regulations identified red food coloring, or Red Dye No. 2, as a possible health risk. The concern stemmed from a Soviet study that erroneously labeled the dye as being potentially carcinogenic. No solid evidence existed, but the Food and Drug Administration (FDA) banned the dye just in case.

Even though M&Ms used Red Dye Nos. 3 and 40, which were considered safe, the company felt that consumers would reject them regardless.

As Coca-Cola found out with their New Coke debacle, consumers do not always appreciate change. Mars was deluged with thousands of letters complaining about the absence of red M&Ms, and some college campuses formed societies to raise awareness of the offense. Some of the letters were from soldiers who served in World War II and fondly recalled M&Ms being a source of comfort, as well as people who learned how to count by taking inventory of their candies.

One man emerged as a real red M&M advocate. His name was Paul Hethmon, and he was a student at the University of Tennessee in 1982. With time on his hands, Hethmon started writing letters to friends inviting them to join the slightly facetious Society for the Restoration and Preservation of Red M&Ms. Membership was 99 cents.

Hethmon had been just 12 years old when the red M&Ms disappeared but told the Chicago Tribune in 1987 that he could still feel the sting of their absence. “You would open up a bag of M&Ms, and your immediate impression would be that there were about 40 billion brown ones in the package,” he said. “It was a really depressing sight, without the red ones.”

The idea took off and Hethmon began holding meetings to stir up support for the outcast M&M. The offbeat story was picked up by a campus newspaper, The Daily Beacon, and eventually made its way to The Wall Street Journal in 1983.

One of the devotees Hethmon recruited was Hans W. Fiuczynski, who happened to be the external relations director for Mars. Fiuczynski was amused by the campaign and clearly took notice of the enthusiasm it was stirring in consumers.

In 1985 and 1986, Mars used some stealth marketing to try and assess the consumer response to red M&Ms returning. They issued red and green M&Ms as part of a limited-edition holiday promotion. There were complaints, but only about the fact the red M&Ms were a seasonal item. Consumers wanted them year-round. They wouldn't have to wait long.

In February 1987, Mars announced that red M&Ms would be returning to bags of plain and peanut M&Ms. Fiuczynski hadn’t forgotten about Hethmon, either. When the news was out, the company sent Hethmon 50 pounds of M&Ms—all of them red.

Mars made another radical change in 1995, replacing tan M&Ms with blue M&Ms. No emotional attachment seemed present there, however, and the change went off without a hitch.

While this might seem like ancient history, quite a few people remember the M&M debacle of the 1980s. On a 2019 episode of the Netflix hit Stranger Things, viewers noticed that the show—which was set in 1985—featured red M&Ms. Maybe they were just holiday leftovers.