Look at this photograph. Can you tell what was used to make it?
What about this one? It has to be some sort of paint, right?
Believe it or not, all of these photographs were created using a woman's menstrual blood.
The artist, Jen Lewis, has used her period blood to create an entire art project called "Beauty in Blood." Her husband Rob Lewis takes the images.
Lewis told BuzzFeed News that she studied history of art in college, and was working at biomedical facility at the University of Michigan when she came up with the project.
Lewis said the more she looked at the flow, she saw different patterns – in the vein of a Jackson Pollack painting. "I got really interested in the abstract qualities," she said.
Lewis and her husband first created the images in the bathroom. But they later switched to creating them in a fish tank.
Lewis's goal for the project is "normalizing the menstruation process" and showing that it can be beautiful.
The project grabbed attention this week after it was featured in the Huffington Post.
She said she is very grateful for the kindness her project has received. "This has been really overwhelming and really positive," she said.
Stephanie McNeal is a social news editor for BuzzFeed News and is based in New York.
Contact Stephanie McNeal at email@example.com.
Got a confidential tip? Submit it here.