The creatures, known as blue dragons or glaucus atlanticus, were found by a passer-by on Fish Hoek Beach near Cape Town.
The animals live off the deadly Portuguese man o' war and other venomous sea creatures - they take the stinging nematocyst cells from their food and concentrate them in their extremities, giving them a far more potent sting than their prey.
Grandmother Maria Wagener, who found the animals, says she often helps beached wildlife back into this sea, but this time her instinct told her to keep her distance.
She said: "I've never seen them before and I've lived near this beach for most of my life.
"They're a bit like a sea scorpion. They are small, about an inch in length. They're blue on the top and white underneath.
"It wasn't difficult to spot them on the white sand."
She added: "I pick up starfish all the time and put them back into the sea but I had a feeling that these would have a sting.
"I probably would have put them back in the sea if I'd had something to lift them.
"So no, I didn't touch them!"
Smart move - because typical symptoms of a blue dragon sting include pain, nausea, vomiting and acute allergic contact dermatitis. Not ideal.
Maria reckons she spotted around 20 blue dragons on the beach, but thinks there could have been even more.
She also saw numerous creatures the blue dragons like to feast on further down the beach.
Maria added: "There were also a variety of other species of sea life.
"There were little blue crabs, Portuguese men o' war, and blue shells called Janthina janthina."
Fortunately for the blue dragons, they didn't need Maria's help.
She said: "They were still very much alive when I saw them.
"The tide would have taken them back to the sea."