Ejecting

Ejecting mass is an ability which can be used to donate cells. You use the key to eject mass, one at a time.

To be able to eject mass you need to have at least 35 mass.

Result
When you eject, all your eligible cells launch mass in the direction of your cursor which acts as normal food and can be eaten by any cell. Cells lose 16 mass per ejection. The mass of the ejected piece is only 80% of the mass lost by the ejecting cell, so cells that eat it gain 12 mass, as 16*0.8=12.8, then the decimal is truncated.

Keep in mind that you lose 16 mass by ejecting, and whoever eats a ejection gets 12 mass. So either way 4 mass of yours is lost to nobody.

Usage
Ejecting can be used to transfer food between your cells or feed allies. It can also be used to create more Viruses. As you can see in the picture, ejected mass has an angle of spread, meaning that viruses you create may veer off course by ~20 degrees. This spread can be lessened by getting closer to the virus, although that increases your risk of eating the virus by mistake or counterattack.

Ejecting mass can be used strategically in team modes to slow down another cell, help an allied cell engulf an enemy, or to prevent an allied cell from being eaten. Friends playing in FFA may also wish to share mass between each other for similar reasons.

Also, ejecting can also be used as a speed boost.

One common strategy is to repeatedly press W when split and near a corner or edge. That way, one of your cells will become much bigger than the other. Hopefully, some small cells will try to get the smaller cell, but then you can split and eat him. Then repeat.

Cell Spawning
Ejected mass has a chance of turning into cell, in other words, there's a chance a cell will spawn into the game with 13 mass (instead of the usual 10) taking the place of ejected mass. They will be the same color as the ejected mass.

Note
Keep in mind that any other cell can eat what you eject, so make sure you are in close range of the cell you'd like to eject to.