Phone actually working without battery???

Okay this is weird... I am new to this Android developing stuff so cut me some slack...
I just took out the battery to restart quickly, but it stayed on... I made sure the battery was far enough away from the device to not be using any sort of black magic. I left it for a while and eventually I just put it back in and rebooted through the menu. What was happening? Draining from the RAM to keep the display on? Some sort of solar panel? I am confused!