what is this?

what is this?

Observation - what is this?. Description: I found this in the (roots) of a clump of moss growing in the filter of my koi pond. There are lots of them. just under 10mm long I know moss dose not have roots.

I found this in the (roots) of a clump of moss growing in the filter of my koi pond.
There are lots of them.
just under 10mm long
I know moss dose not have roots.