Giant Box Jellyfish Could Have Killed 120 People (PICTURE)

Who knew what is essentially gelatine and tentacles could be so terrifying.

Two giant box jellyfish washed ashore in Australia would have been capable of killing 120 people, according to an expert.

The monstrous marine stingers, each measuring 30cm in diameter, were discovered alive by lifeguards at a North Queensland beach.

Surf Life Saving Queensland Townsville region lifeguard supervisor Russell Blanchard said the lethal jellyfish were the largest caught this season.

"I wouldn't say it's a record, but it's about as big as they can get," he said.

Jellyfish found by lifeguards are usually donated to a local university for research purposes. However, the giant jellyfish were so massive the lifeguards did not have any buckets large enough to carry them away from the beach.

The venomous sea creatures were buried in the sand and left to quickly die and decompose, to protect beachgoers.

Jellyfish expert Dr Lisa Gershwin said each of the marine stingers had the potential to kill 60 people, based on the number and length of each tentacle.

She said each jellyfish could have as many as 60 tentacles.

"It takes 3-5m to kill an adult human in as little as two minutes, and as little as 1.2m of tentacles to kill a child in as little as two minutes,'' she said.

The Box Jellyfish toxins attack the heart, nervous system and skin cells. Its sting is so painful that humans have been known to go into shock and drown or die of heart failure after being stung.

Jelly fish