A cedar forest in Japan’s Miyazaki Prefecture is home to a couple of unusual crop circle-like patterns that are clearly not random in nature.

Photos of the bizarre patterns, which are visible only from above, made their way on the internet about three years ago and fueled all kinds of conspiracy theories that involved everything from aliens to secret government experiments. Well, that second one turned out to be quite close to the truth, only the experiments weren’t secret, and they weren’t conducted by some obscure outfit, but by Japan’s Ministry of Agriculture, Forestry and Fisheries. Back in 1973 an area of land near Nichinan City was designated as “experimental forestry” and the results of that experiment are visible today.

One of the experiments carried out in the area involved measuring the effect of tree spacing on growth. They planted cedar trees spaced in ten-degree increments to eventually form ten concentric circles that are increasingly more compact.

50 years later, we can see that the experiment proved that density does seem to affect growth, as the ones packed more tightly together are shorter than the cedars in the outer circles, giving the pattern a concave look. According to Japan’s Ministry of Agriculture, the height difference between the smallest trees in the middle of the concentric pattern and the tallest trees on the outer ring was over 5 meters.

Researchers concluded that trees in less dense areas have more access to resources, while those in the center have to compete for both sunlight and nutrients, which takes a toll on their growth.

The intriguing experiment, almost half a century in the making, is coming to an end, and according to Spoon and Tamago, the cedars in the area, including the two concentric patterns, are due to be harvested in about 2 years. However, following the attention the mysterious circles received on social media, authorities are debating the possibility of postponing the harvesting for a few more years.

For more intriguing tree formations, check out Oregon’s giant smiley face, and the world’s largest signature.