Came across this today, thought it was unusual. Its half an old Whiskey bottle with a tree after growing up through the spout of it. Its on the south buttress on the upstream side of Knockvicar bridge. Will try and get a better shot of it. The tree is not that old but id say the bottle is, it must be on that buttress for years.... Amazing what nature will do :-)
PS. It may not be a Whiskey bottle and may have been used to hold other liquids but the inscription is cool on it: John Leyland of Boyle.