#stromatoporoid

Late Ordovician, Laurentian warm water reef

From top left: archaeocrinus, diestoceras(Oncocerid), isorthoceras, armenoceras

Middle left: tcherskidium and proconchidium brachiopod

From bottom left: aulacerid 2 meter tall sponges, Deloprosopus, phacelloid corals

Researching the environment the Oncocerids lived in, some of the silurian reefs in Gotland, Sweden were primarily comprised of Stromatoporoid sponges.

These were sponges that grew in layers encrusting on rocks, sediments, each other. Creating a reef over time

The ones depicted here are new budding reefs, relatively empty, growing atop a sediment of crinoid fragments

Older reefs would have shared their space with tangles of camerate crinoids, which at the time were abundant and were found to be the most numerous at the reef flanks

Stromatoporoid, Nordegg, Alberta