My stick gives an idea of its size.
The surface had dried into little spikes of mud, up to about 5cm tall, sticking up all over the surface.
The only reason we could think of was that this had been caused by ice forming crystals which had since melted and dried.
We are finding these tubes at all times of year, and they have tiny holes at the top. We now wonder if they are caused by some kind of worm.
22 June 2009
Thanks to Chris Townsend for the suggestion that these mud tubes were caused by Tubifex worms.
16 July 2009
Today I have received a suggestion that these are caused by "bloodworms."
Futher suggestions or conclusions would be very welcome.