I came across this interesting stuffed blowfish. Now you can see why it is called “blowfish” or “ballonfish”. Fugu or blowfish usually have this appearance when they are calm, but when they get angry they inflate themselves until they acquire quite a spherical shape. When they inflate themselves they turn into a balloon with spikes, its poison is one of the most dangerous in the world.
If you travel to Japan and want to try fugu there are a lot of specialized restaurants that only serve fugu cooked in different ways. To recognize a fugu restaurant is quite easy because they usually have an aquarium plenty of blowfish at the entrance to the restaurant:

One of the restaurant waiters fishing a fugu for one of the clients.