Just a quick follow up to a post from a couple of months back of an interesting object I found fishing for steelhead in western NY last fall. I've had several people look at this object and someone actually had a pretty good idea of what it is. It is a stromatolite, a fossilized remain of a colony of blue-green algae. The algae produces a sticky biofilm that catches mud and silt that over time forms a thin layer. Layer upon layer builds up forming these mounds that can appear in in a variety of shapes such as columns, discs, pyramides and rings like a mis-shaped donut. The crack across the top of the object is consistent with it being a stromatolite which would develop as the upper layer of algae was exposed and dried over time as is the western NY location in which it was found as similiar objects have been found there.