Last week Hawaii residents experienced a strange and unprecedented event: millions (perhaps billion) of tiny round, unidentified creatures washed ashore. They were round, about the size of peas, and had a purplish hue. The creatures appeared to be tiny crabs, which for some reason had been washed ashore en masse. (Some surfers reported that the creatures were crawling aboard their surf boards to hitch a ride, which must surely have been an unsettling event.) The event has so far been confined to the south shore of Oahu.
The current best guess as to the identification of these berry-like creatures is that they are a larval form of the Carpilus maculatus crab, better known as the Spotted reef crab or the 7-11 crab. (So called because it has 7 spots on the top of its shell and 4 spots on the bottom.) Although no one is certain why they would be washing up in such numbers, speculation includes a connection to the recent rough weather. The turbulent water may have caused air bubbles in the crabs' shells, which would prevent them from swimming properly. Water currents may also have shifted unexpectedly, causing the tiny creatures to wash up on shore instead of drifting through the ocean as usual.
These small creatures are true cryptids, in that no one can yet provide 100 percent certain identification. Although researchers are fairly confident in their analysis, local researchers, saltwater aquaria enthusiasts, and public aquarium staff have scooped up hundreds of the tiny creatures, hoping to raise them to adulthood in their exhibits and therefore provide a completely certain identification.
You can't entirely fault biologists for being unable to identify these tiny crabs. Many crabs which are familiar to us in their adult forms are completely unknown in their larval form. The ocean is a pretty big place, and thousands of species go through a larval stage which floats loose in the ocean before coming in to shore and coral reefs to mature.
It is difficult, almost impossible to track the various migrations of larval animals through the ocean. These could also be a foreign species which just happened to get blown into Hawaii, instead of travelling on their usual course.
Some people are trying to connect this event to the Fukushima radiation plume somehow. Although since this event only involved one particular species of animal, this connection is unlikely.