Most of the time when milk kefir grains grow or multiple, they show new growth on old grains (where the grains get bigger) or they split off and make new grains. They usually do a bit of both, but typically they split off into new grains while still fairly small. This is what most people think of when they see milk kefir grains:
Even though they may look connected, there's about 4-6 separate grains shown there. Once in a while though, they just keep growing and growing on the same grain and then it ends up being some kind of gigantic grain. This is one of the biggest grains we've experienced. Over 4 inches in length! Fully connected!
Notice that there is one part trying to break off from its mammoth mother. With continued ferments, it will likely spread its wings and break away.
Another unusual growth is when the grains fill with air and become little encapsulated balloons as shown here:
They look beautiful and translucent, however they will eventually deflate and look shriveled and not so beautiful. They may also rise high above the surface during the ferment which is not ideal either.
Grains tend to grow based off the environment in which they ferment (the type of milk, room in the jar, temperature, etc). Small grains, thin grains or shriveled grains may be a sign that they are overcrowded or over fermented. If your grains are unusual in any way, send us a picture. We would love to see it.