An incredible discovery in northern Kenya could have a big impact in our understanding of ape evolution, and consequently our own. Scientists have found a 13-million-year-old ape skull that is amazingly well preserved, so much so that scientists can examine unerupted teeth and the impression left by the brain the skull once housed.

Scientists think the skull was from an infant ape that died in a forest and was subsequently covered by ash from a nearby erupting volcano. It is the best preserved fossil of its kind ever found, and could shed light on ape evolution. It is about the size of a lemon, and the species is named Nyanzapithecus alesi.

“We’ve been looking for ape fossils for years—this is the first time we’re getting a skull that’s complete,” says Isaiah Nengo, the De Anza College anthropologist who led the discovery, according to a National Geographic report.

“Now these questions can be more fully addressed because the newly discovered ape fossil, nicknamed Alesi by its discoverers, and known by its museum number KNM-NP 59050, comes from a critical time period in the African past,” reads a statement from the Leakey Foundation. “In 2014, it was spotted by Kenyan fossil hunter John Ekusi in 13 million-year-old rock layers in the Napudet area, west of Lake Turkana in northern Kenya. … The fossil is the skull of an infant, and it is the most complete extinct ape skull known in the fossil record. Many of the most informative parts of the skull are preserved inside the fossil, and to make these visible the team used an extremely sensitive form of 3D X-ray imaging at the synchrotron facility in Grenoble, France.

“The unerupted adult teeth inside the infant ape’s skull also indicate that the specimen belonged to a new species, Nyanzapithecus alesi. The species name is taken from the Turkana word for ancestor ‘ales.'”ty.