A recent study has documented creepy creatures in an attempt to fill in the patchy scientific record of Australian sea scorpions.
It found that Australian sea scorpions date back to a period called the Paleozoic Era. This was around 541 million and 252 million years ago, before dinosaurs had taken over the planet.
Paleozoic arthropods were some of the largest animals on Earth at the time and would have been found in many oceans all over the world.
According to The Sun, sea scorpions are some of the largest marine predators ever observed in the fossil record.
This included the species Jaekelopterus rhenaniae, which was up to eight foot long.
Experts compare them to modern day great white sharks in terms of how high up the food chain they would have been.
Fossilized remains suggest they could have caught prey in their huge claws and crushed in with the teeth-like structures on their legs. They were also thought to be quick swimmers.
Scientists think they ate fish and smaller arthropods but haven't ruled out the giant scorpions would have feasted on a human if one had been around at the time.
Australia's ancient sea scorpions were first documented on record in 1899.