What is a stream?

What actually defines a stream?  Is it the water flowing on the edge of a bank or a gravel bar?  Does it extend below the gravel and into the soil among the tree roots overhanging the water's edge.  Dr. Deb Finn raises these interesting questions in the Missouri State Mind's Eye.

You can read the story at this Mind's Eye link.  Then for more information on Corethella kipferi, see this 2022 Blog.