Sand patterns made by pufferfish near Amami Oshima, Kagoshima, Japan

© Yoji Okata/Minden Pictures

Sand patterns made by pufferfish near Amami Oshima, Kagoshima, Japan

These sand patterns were first widely documented in 1995, when divers near Amami Oshima, Japan, where this photo was taken, spotted a strange pattern on the seabed. Other divers in the Pacific and Indian Oceans reported seeing similar ‘mystery circles’ in the seabed. And in 2011, humans witnessed firsthand just how they were created: pufferfish. Males of the genus Torquigener work all day for a full week to create the unique patterns, some as wide as 6.5 feet, in an effort to attract the attention of female pufferfish. When was the last time your sweetie made sand-art for you?