Favosites argus from Arkona

Favosites placenta argus (edit 02/02/14) is an easily recognizable species in the field. It's a tabulate coral and forms flat, plate like colonies. The surface of the colony is covered with small calices where the animals would have lived as is typical for this genera. The feature that distinguishes it from other species of Favosites is that the calices vary in size and shape.

Here is a typical small colony that I found in the Hungry Hollow member of the Widder Formation (Middle Devonian) at Arkona.

Note the flat, wavy look to the underside of the colony. This was the result of it's position on the soft sea floor and subsequent spreading.

The calices of Favosites placenta vary in size but always have a pattern of large round shapes surrounded by smaller angled shapes.

Tabulate corals grew by cloning so all individuals of a colony would essentially be the same critter. They would spread by dividing or "budding". Maybe the larger calices represent more mature animals and the smaller calices are the divisions?