How to destroy all objects that connect together like "Puzzle Bubble" or "Dynomite" game ?

My English isn't strong. I would like make game like "Puzzle Bubble" or "Dynomite". Have you ever played ? Many ball connect together I know about Parent but if it have 2 parents that contend many child balls. the last ball shot to put between 2 parents. This 's my problem How to check number of all ball that connect together. I hope you understand me.Sorry about my English. Thank

You can store references to your objects in a grid-like array (GameObject[,]) and then use a simple Floodfill-Algorithm to get a group of objects based on some properties.