Strange corrupt entity in world

I was blowing up Charged Creepers in a test world to see which entities wold die from the explosion and when I did /summon Creeper ~ ~ ~ {Powered:1,Ignited:1} my game froze and went not responding. I closed it down and restarted the world and I got a white rectange-shaped entity floating there. The F3 + B view confirmed it was an entity as it was outlined. In the F3 screen though, it did not show up as an entity. I tried punching it, /kill and even used an external editor to try and remove it but none of it worked. It is stuck there and I can place blocks around it.