Crusting algal and/or bacterial photographed in August 2016 on the bottom of the river "Sèvre Niortaise" in a shallow and well lit place, called "Roman Bridge of <a href="https://en.wikipedia.org/wiki/Azay-le-Br%C3%BBl%C3%A9" class="extiw" title="w:Azay-le-Brûlé">Azay-le-Brûlé</a> "(France). On these crusts various invertebrates, including <a href="https://en.wikipedia.org/wiki/gammare" class="extiw" title="w:gammare">gammares</a> and many <a href="https://en.wikipedia.org/wiki/Theodoxus" class="extiw" title="w:Theodoxus">w:Theodoxus</a> (Theodoxus fluviatilis probably) can be observed. This section of the river is rich in crusting areas that typically form it from horizontal carpet aquatic of mosses (bryophyta) or vertical carpet of <a href="https://en.wikipedia.org/wiki/Marchantiophyta" class="extiw" title="w:Marchantiophyta">Marchantiophyta</a>.
<a href="//commons.wikimedia.org/wiki/User:Lamiot" title="User:Lamiot">Lamiot</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>