i had one that was huge, and needed the space, so i threw it in the sump. ( i know thats a bad thing) I had plans to take it out in a day or two and trade it or something. Well long story short six months go by when i finally get around to pulling it out. It only had a few signs of life on it, and within two months of being back in my tank it is growing bigger than it was before. Don't worry about hurting galaxies. they are virtually indestructible.