Horn coral +

[Bob Saunders]

This horn coral is most likely from the fossil area of Alpena, Michigan per the man that gave it to me. It was covered with very hard dirt. After much cleaning and trips to the ultra sonic machine I am not sure what I'm seeing? The top instead of the usual straight cut like lines has lumps. like the tentacles. And instead of the usual looks of a broken off tail it has the gray as pictured. Is it the normal looks of a well preserved horn coral or another life form attached to it. I understand that they secrete calcium carbonate around them for protection, and that is what we normally find. all images with my cell phone, unedited. 

Thanks, Bob

[Kane]

The black feature is an epibiont, almost assuredly a bryozoan.

[Bob Saunders]

2 minutes ago, Kane said:

The black feature is an epibiont, almost assuredly a bryozoan.

Thank you, I was leaning towards that. Of the few I have self collected and many seen or online I assume this is well preserved or a bit unusual? 

[FossilDAWG]

The coral is a Cystiphyllum.  This genus is characterized by having the interior filled with dissepiments, blister-like structures which form the "bumps", and it lacks septa, which are the structures that form "lines" in most other genera of rugosan corals.

 

Don

[Kane]

1 minute ago, Bob Saunders said:

Thank you, I was leaning towards that. Of the few I have self collected and many seen or online I assume this is well preserved or a bit unusual? 

Not too unusual. Bryozoans tend to grow on anything that doesn't move too fast, as they themselves are adapted to a sessile lifestyle.  

[Rockwood]

I disagree with the idea that the bryozoan was growing on the coral. The way I see it, it would be just as likely that the coral was growing on the bryozoan.

Either way things must have been tense.