CT scans can be great for getting an internal view of humans—and anything with bones, apparently. According to Wired, Adam Summers is on a mission to take a CT scan of every species of vertebrae on the planet.

That’s a mammoth task, so he’s starting with fish. The first goal is to catalogue all 33,000 species of ray-finned fish, including species such as tuna and bass.

The scans are done using x-rays and can take several hours each, so Summers developed a method to scan 10 to 20 different fish (mostly taken from museums at this point, as some of the variations he wants to capture are already extinct) at once. He wraps the fish into ethanol-dipped cheesecloth and rolls them up like a burrito. The end result is a three-dimensional digital replica that can be used in 3D printing or scaled up and down for more precise examination.

The point is to create a non-invasive record of living things on Earth, according to Summers. The environment is changing rapidly, and this could help record what kinds of animals were here at this time (or shortly before it). Plus, the ability to examine the scans can help researchers come to understandings in various parts of science, including human medicine.

Check out Wired to see more about why Summers is on this mission, and how he and other scientists are tackling the problem of his bigger all-vertebrae scanning goal—including how to scan a blue whale.