Where does mass go?

In agar.io, sources of mass are abundant. The little pellets of nutrition spawn frequently. The problem is that there are no places for mass to go - which it must do otherwise the game would run out of space. Even when people log out, their cell remains stationary until it is eaten. I'm assuming then that mass must be lost in one of the following situations:

• When splitting (via space)
• When popped (via a spike)

Is this the case? If so, how much of my total mass is lost when this happens?

Solution 1:

Thanks to Ardaozkal his comment I was able to do some research.

There are a couple of reasons why the game never runs out of space,

• When just going around not collecting any orbs you seem to lose a bit off mass. The amount of mass you lose seems to be bigger if you have a lot.
• When pressing W you shoot out a bit off mass, picking it back up will not give you back the amount you lost.

Splitting up or hitting a spike does not seem to make you lose anything other then your shape.