Salps, seen here connected in a chain-like formation, are common in ocean waters around the world. Creative Commons

What’s a day of fishing without something unexpected happening? That was the case for a New Zealand father whose daily fish limit probably didn’t include strange sea creatures.

The U.K.’s Mail Online reports that Stewart Fraser was fishing with his two boys 70 kilometers off New Zealand’s Karikari Peninsula when something in the water caught his eye, an unknown marine creature swimming around near the boat. Hesitant at first to bring it aboard, Fraser eventually caught the bizarre, translucent, sea cucumber-shaped animal and took some photos of it.

“I was in two minds whether to haul it in, but curiosity got the better of me and I decided to take a closer look,” Fraser told Mail Online. “It felt scaly and was quite firm, almost jelly like, and you couldn’t see anything inside aside from this orange little blob inside it.”

Had Fraser found an unknown alien being? Had some ancient creature that had resorted to living its life in the deep suddenly resurfaced? Not exactly.

Turns out, while the animal Fraser caught certainly looked strange, it’s actually quite common. According to a National Marine Aquarium biologist who spoke with Mail Online, Fraser had snagged a salp, a barrel-shaped, gelatinous marine invertebrate that feeds on phytoplankton.

'They have an interesting life-cycle with alternate generations existing as solitary individuals or groups forming long chains,” the biologist explained to Mail Online.

While common in seas throughout the world, humans rarely interact with them because they’re so hard to spot. Their seemingly transparent bodies render them nearly invisible in the blue water. But the salp likes it that way, because what better camouflage from predators is there than invisibility?

Salps are actually a very important player in the Southern Ocean food chain. According to recent reports, in the last 30 years, scientists have observed a tremendous increase in the number of salps surrounding Antarctica.

Researchers think the increase in salp, which feed in open waters, could be due to a decrease in Antarctic sea ice due to climate change.