It is strange. When I grab one they shrink into the shell/exoskeleton. I can pinch the tip a little and it feels like plastic. If it is a shell they made from their environment all there ones I've seen have the same source. When they swim it does look like it's a kind id worm inside the shell. I've attached a picture of one in the shell. 

It's not a damselfly larvae or Dragon fly larvae. They don't look like that.   Have you caught it yet? If you catch it, see it the long green part is a plant the larvae is hiding in. If you can separate the green part from the larvae, it's a caddis fly.  Now I'm all curious to find out what it is.

Well, I’m not sure that he babies are half size. They are probably around 1/4-1/2.” Everyone is healthy, and I’ve been able to count 9 babies at one time. Hoping the now 3 new mamas drop soon! Eggs still look fairly brown.

Another vote for caddisfly??? I always forget what they're called, but they do build homes for thesemlves which help them blend in and protect them from predators.

I uploaded a video to YouTube.  I don't  think it's a dragonfly or damselfly. Those have bulging eyes