It's something no one has seen before, in fact, it seems no one is definitely sure what they are.
Biologists at the Waikiki Aquarium are puzzled, and they have been getting reports of the crabs from Kahala to Ala Moana, all this week.
"The lifeguard called and asked what these things were because she had reports of surfers were actually have these things crawl up on their boards and onto them," says Norton Chan, Waikiki Aquarium Biologist.
He can't find a specific name for the animal - all he knows is they are some type of crab still in the larvae stage.
"What you are seeing is a swimming stage probably a few more molts before they settle into their actual crab stage itself," says Chan.
Aquarium officials are saving some, hoping to keep them alive long enough to see how they grow.
So, here's what we know- absolutely nothing.
It's unknown where these crabs came from, how big they'll get and what they eat.
