I know you were wondering, so I went ahead and did the research for you.
This is a lightwell. A priest makes it, and it will heal you up when you are running out of fire. You don’t need to lose your dps target or anything – you just click on it as you run past. You don’t even have to run terribly close to it.

This is a mage table. Mages (natch) make them. They are filled with yummy yummy cakes, which will heal you up, but you have to sit down and sit still, and not be in combat to eat them.

Do not mix these things up. Especially when you are running out of fire.