Blue-ringed Octopus

They are found between Japan and Australia. It is 5 to 8 inches small ( 12 to 18 cm).
It has about 50 to 60 rings in its body and it is known as the most venemos marine animal.
Its venom is powerful enough to kill a lot of humans. There is no blue-ringed octopus cure available.
A few minutes after the bite you would be paralized, you would stop breathing, but your brain would continue working, so you would realize what is happening.