I was super excited to discover some fossils on Oval Beach in Saugatuck, Michigan (USA) that are highly unusual to find in winter. The sample below is an extinct tabulate coral, a reef building colony type coral called halysite. But we often find these saltwater varieties from the Paleozoic Era on our fresh water Lake Michigan shores. To explain this phenomenon I’ve written an article entitled “I Found a Fossil on the Beach and Wondered” at hubpages.com where I’m also the Fossillady. A link is provided in the box to the right.
This halysite coral is easy to distinguish due to the chain link appearance coining it with the common name “chain coral”. It was lying under layers of sand that aren’t usually exposed during the winter months. But the mild weather with little snow has allowed winter winds to push sand off the under layers. It’s also due to low water levels from a long dry spell during summer 2012, there’s more beach to explore.
The extinct halysite corals displayed small tubes from which resided the jelly-like coral animals called polyps. The coral polyps contained stinging cells for protection and also grasped plankton food that passed by in the ocean currents. As the halysite corals grew, they built up walls of tube-like chambers called theca which steadily multiplied adding more links to the chain. In their hay-day as they continued to multiply, they built large limestone reef structures on the seabed. They thrived mostly during the Silurian period up to 425 million years ago!
Phylum: Cnidaria (means stinging animal)
Class: Anthozoa (means flower animal)
Order: Tabulata (possess inner horizontal dividing walls from growth patterns)
Family: Halisitidae (means chain coral)
Genus: Halysite Species:unknown