Thats wierd, whatever I put in my tank usually gets too big and I have to give it away. Even the extreamly common mud snails I collect here in tide pools seem to live forever. But I do lose some of the smaller hermit crabs. When I got this pair I also got 5 others with them, they stayed much smaller and disapeared one by one over those years. I just picked up 5 of them today, I will have to see how long they live. This batch seems kind of stupid and slow. I doubt they wil last long. The ones that I lost were much faster and they knew how to text.