Dear all, we found these empty cylindrical cocncretions in severals ponds and lakes from different mountain range in Uzbekistan.
Any ideas of what it could be ?
The pictures have been took under binoculare lens (the structure are from 0.1 mm to 0.5 mm).
May be a root concretion of Cyperaceae or other hydrophytes from the ponds ?
Thank you for your help,
Lucas