Found in SE Michigan, but likely moved there by man as it was in my mothers new condo flower garden.
Approximately the size of a grapefruit. Spheroid with a mushroom shape with the bottom "stem" area not having any of the corallite tubes.
Originally thought it was a Petoskey stone, but after cleaning it up (hosing the mud off it) I cannot see any separation between the tubes, and I have never seen a Petoskey with such far separation of the openings and without a very clear hex shape. Matter of fact, I cannot see any joint between the openings at all.
The other types of corals from the area I am familiar with (horn, Charlevoix, and chain corals) it is clearly not one of them.
Any help at an ID would be appreciated. Will try to post a couple other pic's below, hit the size limit with this post.