1. Harvestmen (better known as daddy longlegs) are classified as arachnids and have just one set of eyes.
2. But a new 305-million-year-old fossil found in France shows that these ancient arachnids had four eyes, according to new research published in Current Biology.
(Merciless teasing from other arachnids was not reported.)
3. Arachnids can have two different kinds of eyes either on the side (lateral) or toward the middle (median) of the body.
4. The new harvestman fossil, shown here in a high-resolution x-ray, has both.
5. Modern (and adorable) harvestmen embryos only have a single pair of median eyes.
The white arrows show lateral eye-field areas, which never actually develop. The black arrows show the domains that eventually form the median eyes.