NOTE: This feature has been replaced with Spawners and is no longer in the game.
The Mother Cell was a temporary addition to Experimental Mode added on 2015-06-11. At first it seemed to be simply a larger version of the virus, but with a few differences. Located in the center of the map, it was the size of a ~5000 mass cell and ejected 10%[1] \ 1/7[2] of the map's food in random directions around itself. The mother cell could not be pushed or moved through. The large amount of food surrounding the mother cell led to a high concentration of smaller cell activity, which brought larger cells to the mother cell as well. Using the mother cell for food/hunting was a high risk, high reward activity. The mother cell had a limit of 10.000 score, unlike Spawners, which can grow larger than the map.
The Mother Cell was removed from Experimental Mode the next day, on 2015-06-12, and was replaced by a similar mechanic named Spawners.