In the mangrove swamps of Puerto Rico, four eyes are permanently fixed on the sky. These eyes are surprisingly similar to yours. They’re assembled using the same genetic building blocks, and they have lenses, retinas and corneas. But their owner couldn’t be more different – it’s a box jellyfish, and it’s looking for some shade.

The box jellyfish (Tripedalia cystophora) is far from a simple blob with tentacles. It’s an active, manoeuvrable predator, and it finds its way around with no fewer than 24 eyes. Scientists have known about these for over a century, but people are still trying to work out what they do.

The eyes are grouped into four clusters called rhopalia, each containing six eyes. Four of these