I have a had Cerith snails for quite awile. They used to lay eggs all of the time. So when I saw very small white snails patrolling the tank I assumed thay they were small Ceriths. However, these never seem to grow, and the don't look like Ceriths. They look more like Tonga Nassarius snails. Maybe I bought some at the fish store awhile back. I don't rember having adults. But I have a lot of small ones. I have had groups of them for a long time now. They don't seem to get very big. Like a quarter inch tops. I can't take pics tonight the lights are out. But they look like this.