Minecraft wiki entry for Blaze, associated text: Blazes can see the player through walls, like spiders and slimes.
When throwing a potion of Invisibility on a blaze, the smoke remains visible.
According to Jeb, blazes look the way they do because all mobs in Minecraft are cuboid-shape, so to make them flame-like and magical, he created them as a core surrounded by rotating rods.[2]
Blazes originally didn't have eyes when Jeb was first creating them and "just looked like a yellow rock". Eyes were added to "give it more personality".[3]
Despite not having visible feet, blazes are still capable of making footstep sounds.[4]
According to Minecraft's "Visit the Nether!" blazes are sentient beings made of pure lava. The article theorizes they were created by the original inhabitants of nether fortresses to serve as guards, but their creators lost control over the blazes and were subsequently destroyed by them.[5]