anyone know what this is ??

Hello,
I found this and many others while removing rocks during pond makeover. They seem to be constructed of grains of sand. The tube shaped cacoon type things were under water, attached to the rocks.
Thanks,
Lisa

Yep, you've got caddis fly larvae in your pond. They are nondescript insects with wings that have larvae that are water dwelling. They build their little homes out of sand, gravel, etc. There are many different species. They are actually pretty cool until they turn into caddis flies. Then they are fairly boring.