Octopuses have blue blood, three hearts and a doughnut-shaped brain. But these aren’t even the most unusual things about them! Known for their otherworldly look and remarkable intelligence, octopuses ...

The brain tissue model consists of a 6mm-wide donut-shaped sponge-like material made of silk protein and collagen, suffused with neural stem cells, which are then coaxed into mature neurons ...

The giant squid’s gullet passes through its doughnut-shaped brain. This means it cannot swallow large pieces of food. Giant squid have a parrot-like beak between their eight arms and two tentacles.