Billy Bob Thornton explained why Angelina Jolie wore a vial of his blood around her neck during marriage

Billy Bob Thornton has explained why Angelina Jolie wore a vial of his blood when they were married.

The pair tied the knot in 2000 before divorcing three years later.

It's believed the couple split pretty amicably, with Jolie explaining in 2008 that she still 'loved him dearly' and was 'proud' to have been married to the actor.

While together, the pair were sometimes apart while working on their individual projects, but they had a rather unusual way of staying connected.

As a romantic gesture, Jolie wore a 'vial' of Thornton's blood around her neck and the filmmaker has since explained why.

Speaking to students at Loyola Marymount University's School of Film & Television in 2014, Thornton said: "[A] vial of blood is very simple. Angie came home one day with a kit she bought.

"You know those lockets you buy that are clear and you put a picture of your grannie in it or something like that and wear it around your neck? That's what it was. She bought two of those.

"We were apart a lot because she's off making Tomb Raider and I'm making Monster's Ball. We were on opposite ends—we see each other for two weeks and whatever.

"She thought it would be interesting and romantic if we took a little razor blade and sliced our fingers, smeared a little blood on these lockets and you wear it around your neck just like you wear your son or daughter's baby hair in one. Same thing.

"From that we were wearing quart jars of blood around our necks."

The pair were married for three years (SGranitz/WireImage)

Jolie has since shared her side of the story, explaining that it was more a 'flower press' than a vial.

In 2008, she told Entertainment Weekly: "It was never a vial... It was like a flower press.

"It was like from a slight cut on your finger and you press your fingerprint in. It was kind of a sweet gesture. I thought it was kind of romantic!"

She added: "I still love him dearly and think the world of him and I'm proud to have been his wife for a time. I don't believe in regrets. It's a dangerous habit to get into—it makes you pause in your life if you start thinking back and questioning yourself."

The pair have since explained why Jolie wore the vial (Frank Trapper/Corbis via Getty Images)

Jolie went on to meet Brad Pitt in 2004, when they were shooting the movie Mr and Mrs Smith.

The pair struck up a relationship, going on to get married and have six children before splitting in 2016.