End portal

Air Portal is a block that was added in Beta 1.9 pre-release 3. It has a very strange appearance, which can be best described as a portal view on a virtual black floor with blue star-like particles on it. It also emits light and black smoke. Only the top and the bottom sides of the block are visible, the bottom side looks like stone.

It's purpose is currently unknown.

The game will crash when you move the cursor above the block in the inventory, because it is a illegimate block and there is no tooltip for it. The Modder Ashtheking has released a temporary fix for this: http://www.minecraftforum.net/topic/691344-19-pre3-ashthekings-ender-goo-fix/