A scene from “Marcel the Shell with Shoes On.” Photo courtesy of A24 via AP

Crafted out of a hermit crab shell, a googly eye and a pair of pink Polly Pocket tennis shoes, Marcel the Shell leaves an outsize impression that belies his one-inch stature. Dean Fleischer Camp realized as much in the summer of 2010, when the first audience was introduced to the stop-motion character’s trembling timbre and infectious positivity.

After promising he’d make a video for a friend’s Brooklyn comedy show, the filmmaker got his then-partner, “Saturday Night Live” alum Jenny Slate, to riff in character as a minuscule mollusk in a big world. (One quip: “Guess what I do for adventure? I hang-glide on a Dorito.”) Dropping Slate’s voice in Marcel’s roughly sketched mouth, Camp delivered a three-minute mockumentary that played as amusing, absurdist and, to his surprise, delightfully disarming.

“It was kind of an arty, judgmental crowd there, so I was not expecting them to melt over this cute little guy that we created,” Camp says during a recent Zoom interview alongside Slate in Los Angeles. “When I saw their postures loosen, I was like, ‘Heh heh heh, gotcha.’ And I just felt like if it can melt the cold hearts of Brooklynite art-scene people, it can go places.”

The feature film version of “Marcel the Shell With Shoes On” was written, from left, by Nick Paley, Jenny Slate and Dean Fleischer Camp. Photo for The Washington Post by Allison Zaucha

Twelve years, two more shorts and 48 million YouTube views later, the character has spawned a feature-length film: “Marcel the Shell With Shoes On,” directed by Camp, starring Slate and co-written by the duo with Nick Paley. Acquired by art house haven A24 out of last year’s Telluride Film Festival, “Marcel” scurries into D.C. theaters this weekend.

The diminutive character’s big-screen journey could’ve easily happened much earlier or not at all, as Camp and Slate – who were married from 2012 to 2016 and remained creative collaborators after their divorce – went through many a meeting with executives who were looking to monetize Marcel. Rather than compromise on a studio-driven film adaptation, about Marcel getting lost in Paris, fighting crime with Ryan Reynolds or embarking on some other bombastic escapade, the duo developed the sequel shorts and penned a pair of Marcel-centric picture books.

“It just never felt like the right way to go forward,” Slate says of the studio system. “It always felt like the conversations were about making Marcel different or pairing him with an important male human actor. We believe, because we live with the character in our minds, that he himself is enough and that his world is enough.”

Eventually, Camp and Slate found a fitting financer in Elisabeth Holm, who produced the Slate-starring indie darling “Obvious Child.” The filmmaker-friendly nonprofit Cinereach and other production companies then boarded the project as well.

“We found the total right partners,” Camp says, “who believed not in Marcel as, like, a potential new ‘Minions’ but as himself.”

Although Marcel was the only animated character in the original shorts, the film visualizes an entire community of anthropomorphic shells – including the elderly Nana Connie, named after Slate’s grandmother and voiced by Isabella Rossellini – among other stop-motion creatures. But the movie stays true to the shorts’ spirit, with the story mostly set in Marcel’s humble home and Camp again playing a fictionalized version of himself. The plot is a simple one: Separated from his family, Marcel tries to use his newfound viral stardom to track them down.

While Camp and Slate did consider some grander concepts, such as Marcel enrolling at a music academy, it was Camp’s friend and collaborator Paley who helped pinpoint the more poignant premise. In addition to revisiting some of the shorts’ most memorable gags, the movie finds new ways to mine the character’s whimsical nature and minute stature for laughs. Cutting through that humor, however, is something deeper: a heart-rending character study about the fear of the unknown and the beauty of everyday existence.

“The shorts are mainly jokes, but there is something that people respond to, including myself, that’s melancholy,” says Paley, an editor, writer and director who worked on “Inside Amy Schumer” and “Broad City.” “He’s alone, it’s so quiet, and he’s so small and the frame is often so big. You feel drawn to him because there’s a vulnerability that he doesn’t fully acknowledge himself. He’s living at the periphery of human life and he has every reason to be scared, but often he’s very brave.”

Staying true to Marcel also meant honoring the DIY, improv-heavy process that shaped him. For the film, it was a cyclical method: After capturing recordings of Slate ad-libbing her way through certain scenarios, Camp and Paley would take that audio, edit it down, build a scene around it and circle back for another session with Slate.

“Sometimes the scene would stay intact,” Camp says, “and sometimes Jenny would improv and find a new angle on it that worked better.”

“Or go on a tangent,” Slate interjects, leading a chuckling Camp to affirm: “Or go rogue.”

And Slate wasn’t the only improviser. Audio in the movie of Nana Connie discussing her garden was recorded on location at Rossellini’s Long Island home, as the veteran actress guided the filmmakers through her own lush estate. When Marcel’s story catches the attention of “60 Minutes,” those are real crew members from the show – without a script, told to go about business as usual – coming to interview him.

“If you were to really isolate the dialogue track in the movie, you would hear us drinking coffee, and planes and lawn mowers and stuff,” Paley says. “That was all built into the premise of it, which is to make it as (documentary) as possible and contradict that with the intensive care it takes to stop-motion animate something – something so free and something so process.”

Considering that idiosyncratic approach, it’s no surprise that Camp and Slate describe the film as a deeply personal endeavor. When Marcel becomes a social media phenomenon, his emotions mirror Slate’s own bewilderment about online eminence. Breakups also loom over the story, as Camp’s documentarian character works through a recent separation. Slate and Camp both say that Marcel’s journey of love, loss and learning to move on was derived from recent experiences in their lives.

“A lot of people have said, ‘Did you make this movie in reaction to the pandemic?’ And no, we didn’t – it started way before then,” Slate says. “But I think it speaks to the fact that people feel isolation, people feel the largeness of how their grief progresses and their life progresses, and that is something that’s really constant. Our lives were changing, too, in so many ways, and that all ended up in there.”

“I always try to make personal work because you have to,” Camp adds. “You won’t be sustained for seven years – which is how long it took to make this movie – if you don’t.”

That catharsis made Camp and Slate all the happier that they didn’t surrender control of Marcel in the wake of the first short’s popularity – though they could’ve used the boost in exposure. (“Even still!” Slate exclaims. “I’d be fine with a career boost.”) Examining the finished film, Camp believes now more than ever that their vision “would have completely died on the vine at a studio.”

“I think that’s what happens when you really love something, is that it’s enough for you,” Slate says. “If you know it well enough, you can tell when the connection is stressed or when it has become compromised in one way or another. I don’t think I’ve ever really experienced this again in other things. But with Marcel, he feels like our family.”