Last summer, comedian Jenny Slate didn't know if her Saturday Night Live contract was going to be renewed. "Eventually, I got to a point where I just really wanted to create something," she says. That something turned out to be the adorable, three-minute-long Marcel the Shell With Shoes On, a stop-motion-animation film about a precocious shell — voiced by Slate, 28, and directed by her live-in boyfriend, Dean Fleischer-Camp, 26. ("Guess what I use to tie my skis to a car?" Marcel squeaks. "A hair.") Since August, Marcel has racked up more than 4 million YouTube views, won the American Film Institute Award for Best Animated Short and was accepted at Sundance. The couple have sold two Marcel books to Penguin's young-adult imprint and are developing a TV show about Marcel and his friends. "It's sort of documentary-style," says Slate. "The other characters all have really good personalities except for one. And one is based off of one of my favorite people in the world — my grandmother."