Free images results:

Cluster pictures, stock photos and images


Marbles Stock Image
Author: Southpaw3
Inky cap Stock Photo
Author: Wilmy

Also, here are some commercial RF-licensed images that match your search criteria:  
Crab Cluster Royalty Free Stock Image
Author: Dole

Explore more commercial options: More Cluster Stock Illustrations & Vectors | More Cluster Stock Video Footage