Listener questions are the heart and soul of WGBH's Curiosity Desk, and WGBH reporters are just as curious as any other WGBH listener. Recently, WGBH News' Craig LeMoult reached out to the Curiosity Desk in the hopes of finding an answer to what turned out to be a fairly dirty question.

As a professional reporter, LeMoult is trained in the art of "getting to the bottom of things." But when he recently tore down an old shed in his backyard, he came upon a head-scratcher at his feet.

"I would describe it as essentially looking like a manhole cover," said LeMoult. "And there are words on it. It says F.B. Jones, Somerville, Mass."

There's a hinge on one side of this "manhole cover," and a foot pedal on the other. If you step on it, it pops open, revealing a big metal bin inside a concrete lining.

"So my question is: What the heck is this thing?" asked LeMoult.

This thing — put simply — is an old garbage can. Its technical name is a subterranean receiver. And LeMoult is not the only resident in the area to stumble upon one of these is his yard. Back in the early-to-mid-20th century, they were a staple of life around here.

"Yes, definitely ubiquitous," said Jack Leydon, who grew up in Somerville in the era when the F.B. Jones Company’s subterranean receiver was king. "Everyone had an outdoor, underground garbage pail."

Today, we use words like trash, garbage, refuse and rubbish interchangeably — but in Leydon’s day, garbage meant garbage.

"This is not going to be news to anybody over a certain age, but no civilized person would throw their garbage in the rubbish," he explained.

Rubbish was dry trash that would be tossed in metal pails for curbside pickup — much like today. Garbage, on the other hand, consisted of food scraps and organic material — all that gross wet stuff. And it was the garbage — specifically — that these receptacles were designed to keep hidden away until it could be dealt with.

"We would not just see the truck, but we literally could smell it a good couple of hundred yards away," recalled Somerville Alderman Jack Connolly. "Most noticeably in June, July and August — it was extremely fragrant."

When Connolly was young, the garbage men came through twice a week. And it was grueling work, pulling heavy, garbage-filled, metal bins up from the ground, lugging them from the backyard to the garbage truck at the curbside, emptying it, and then returning it, at house after house.

"The guys were very strong, burly guys and their forearm size would be gargantuan," said Connolly. "I always think of Popeye all the time with those massive forearms. And that’s what these guys had."

F.B. Jones patented his first version of the subterranean receiver in 1911, and in the early and mid-20th century was churning them out at 22 Webster Street in Somerville. Here they mixed the concrete for the lining, and manufactured the metal bins and heavy lids emblazoned with the company name.

But why was food waste — specifically — dealt with in this manner? And what happened to this system of disposal?

Back in the 1930 and 40's, it was common practice across the U.S. to feed food waste — a.k.a garbage— to pigs. At least 60 cities and towns in Massachusetts did this, according to Heather Rodgers’ "Gone Tomorrow: The Secret Life of Trash." But feeding pigs is not why food waste was so fastidiously separated out. After all, this is also the same era when tons of Boston’s garbage was being dumped on Spectacle Island. The reason is that it was best way to deal with it at the time.

"There were no disposals or mechanical garbage grinders," said Michael Levy, who grew up in Brookline in the F.B. Jones years and had a subterranean receiver in his childhood home. "So you kept the garbage separate, and you put it in this garbage pail."

Storing the garbage underground kept it a little cooler, and that heavy metal lid kept rats from getting into it. And while it didn’t eliminate it, it did help to reduce that awful smell, and it also helped reduce attraction from flies and maggots. And while the garbage disposal did move the needle a little, the real game changer for garbage came in the 1960s, with the advent of the plastic trash bag.

Initially invented by two Canadians for waste at Winnipeg General Hospital in 1950, plastic trash bags first hit the consumer market in the 1960s. Plastic bags quickly proved so adept at containing garbage, that not only could it be kept safely above ground in curbside bins, it could even be mixed in with the rubbish.

Today, plastics of all kinds — from bags, to water bottles to straws — are in the cross-hairs for their contribution to global pollution. And towns like Cambridge actively encourage residents to once again separate their food waste from other trash. So maybe these old receptacles aren’t just artifacts of the past — but also a guide for the future.