Unidentified coral fossil -Maryland

[Thatbirdguy321]

Recently found this coral fossil which seems to match rugose corals from the Carboniferous, however it was found in the lower Chester River, Maryland, which is considered Paleocene. I was also suggested ‘eridiphyllum’ and ‘disphyllum’, also from older than expected periods.

[TqB]

Welcome to the forum.

It's definitely a Paleozoic erratic colonial rugose coral and it does look silicified.

It's very hard to tell the period as there's so much homeomorphy in corals. Acinophyllum (Devonian) is a good possibility and it's close to some Diphyphyllum from the Carboniferous. (Beware of Diphyphyllum though - it's been used historically for a lot of similar N. American corals that are probably something else.)

Edited February 25 by TqB

[Rockwood]

If this was close enough to the Atlantic for sailing ships to have docked it could have been from discarded ballast. 

[Thatbirdguy321]

The Chester River was a significant port river in the early days of the US, I believe it held a similar role to today's Baltimore, so ships would be coming in and out regularly.