Sophie Thatcher’s handbag is full of tangible memories. She called out pictures, a pair of earrings from her boyfriend and “old things I keep in there.” Finally, she found what she was looking for: a handmade sculpture, repurposed into a necklace, so precious that she feels it’s safer to carry it in her bag rather than wear it around her neck.

Her identical twin, Ellie Thatcher, a multimedia artist who specializes in claymation, originally made the sculpture for an Avey Tare music video. (Avey Tare is also a member of the band Animal Collective.) She later added the chain and gave it to her sister when the two were living in different cities.

“I’m a very nostalgic person, so I think that’s why this gift was just kind of perfect,” said Sophie Thatcher, who is the star of A24’s new horror film “Heretic.” In an interview that has been edited and condensed, Ms. Thatcher talks about the “twin effect” and the necklace that links them together.

Tell me about this necklace.

I don’t usually wear it out. I’m a little scared of the string, but it’s always just in my purse and travels with me to different places. Ellie made it two years ago. It’s kind of just a reminder that I have a very talented sister and it’s just so nice to finally collaborate and have her be in the same city — she was in Chicago, I was in L.A. Now that she’s in L.A., I’m just thankful to have someone that’s talented and cares. It kind of almost feels like I don’t need friends, which is dramatic, but it’s kind of the twin effect.

Since you don’t really wear it as a necklace, do you ever think about framing it?

Yeah. In my house, I have a whole row of just antiques. Most of my house is essentially an antique store. There’s a lot of just knickknacks and things that mean something to me, so I might try to frame it and place it up there. It is dangerous to have in my purse. I know that.