Debuting in the 2010 short film titled Marcel the Shell with Shoes On, the titular Marcel is an adorable little stop-motion shell with a googly eye and an appreciation for a world far vaster than himself. Directed and co-written by Dean Fleischer-Camp, the short starred Jenny Slate (who also co-wrote the script with Fleisher-Camp) as Marcel, and quickly became a cult classic. Now, Slate steps back into Marcel's tiny shoes, bringing the character and his world to the big screen in Marcel the Shell with Shoes On alongside some welcome fresh faces, like Isabella Rossellini as Marcel's last surviving family member, Connie.

During an exclusive interview with CBR ahead of A24's Marcel the Shell With Shoes On's Jun. 24 premiere in theaters, Slate and Rossellini reflected on the importance of improvisation in crafting the bond between Marcel and his Grandmother Connie. They also discussed the challenge of not letting critical response -- either positive or negative -- define the release of such an emotional story.

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CBR: What was it like working on this film together and discovering the bond that defines Marcel and Connie's relationship?

Isabella Rossellini: That, for me, was a very new experience. Because generally, you get a script, you memorize the lines, you're trying to make them natural, and it's spontaneous. That's what an actor does. In this situation, there was an outline of the story. But Jennifer and I did a lot of improvisation. So that was a completely different process. It's amusing and fun and adventurous and curious, and I didn't know what to expect. It was a long time between the improvisation and when the film was finally made because they first had to edit the sound. And then they had to film the live-action and then the stop-motion. So it took a long time.

Jenny Slate: I love to improvise. I just felt quite honored that Isabella would join in with me. It really felt, Isabella, like when you'd first arrived, you said, "Okay, let's go." That is so exciting when you get to work with an actor that you really respect, but you have to create the moment together. When you have a script, and you show up, and there's an actor that you love so much, you can lean on the scripts -- but when you really only have each other to make sure that the story even appears, you know that that feeling of connection is a really big privilege. The story is the way that it is, not just because of what I add as Marcel but because of the irreplaceable thing that Isabella adds as Nana Connie.

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I loved the film, and I'm not the only one -- at the time of this writing, it's currently at 100% on Rotten Tomatoes. What is it like to see the response to the film be so positive?

Isabella Rossellini: So far, so good. I've seen it be loved by the journalists, the friends who have seen it. But of course, it's this weekend that we will see.

Jenny Slate: Yeah, I'd say that that's so true. I think, for the most part, just keep for yourself what you know you liked about the work and why you do it. Because wouldn't it be such a tragedy if like, right now, I was feeling great. But then you know, a bunch of people couldn't make it to the theater this weekend. And then suddenly, I threw it all away. You know, that seems really short-sighted. But I think that in the end, the fact that everybody else really likes it, that's very nice, but it's also for them to hold. I'm not really sure what to do with it. I know what to do when someone says 'you got the part!' Then I feel proud, then I get all my energy up. I can't wait to go to work. I can't wait to expend that energy on this art.

But it's always been hard for me to properly receive a compliment. I think it feels that same way that, at once I have full belief that people should enjoy this movie otherwise I wouldn't have made it at all. I don't really like to half-ass anything. We did it on purpose, and it's nice, but I'm not exactly sure what to do with it that isn't more than what I'm already doing. I enjoy my daily life with my little baby and my husband, and I live in Massachusetts. You know, that's kind of where I am.

Enjoy the sweet ride of Marcel the Shell with Shoes On in theaters on June 24.