Another item that my friend Christian sent me was this giant Heliophylum coral. It is a little over 6in (15cm) long and nearly 3in (7.5cm) wide.
One side looks totally normal for a horn coral....
..but as you turn it you can see that one side is nearly flat.
This was the cup of the coral
The flat nature of the fossil is not a growth limit nor typical for the genera, rather it shows that this coral sat exposed on the seafloor after it died and toppled over. Time enough for the exposed surface to be eroded away before it finally became buried. I like fossils like this as it gives you some insight into the environment in which these animals used to live.
The fossil came from the Visby limestone near Häftingsklint on the island of Gotland, Sweden. The rocks are dated to the Wenlock stage of the Silurian.