What's this fossil, found on a boulder along Lake Ontario?

[Rogue Embryo]

Found this fossil on a boulder along Lake Ontario in Toronto. About 5-6 cm long. Thanks for help identifying.

 

[Tidgy's Dad]

Solitary rugose coral, I believe. 

[FossilDAWG]

Definitely a solitary rugosan coral.

[Rogue Embryo]

Thanks, makes sense. I just thought that rugose coral would have more of a cone shape.

Camille

[val horn]

What about calamities ?  It is a cylindrical shape with obvious joints between sections with vertical lines along the lengths.

[Earendil]

2 hours ago, val horn said:

What about calamities ?  It is a cylindrical shape with obvious joints between sections with vertical lines along the lengths.

I don't think the provenance is right for Carboniferous plants. No shale for plant fossils. Besides, it doesn't look like a Calamites. The 'segments' are too close together.

[Kane]

3 hours ago, val horn said:

What about calamities ?  It is a cylindrical shape with obvious joints between sections with vertical lines along the lengths.

There are no Carboniferous outcrops here in Ontario. 

[Rockwood]

1 hour ago, yardrockpaleo said:

, it doesn't look like a Calamites

 There you go.

[Ludwigia]

11 hours ago, Rogue Embryo said:

I just thought that rugose coral would have more of a cone shape.

 

Not necessarily. Here is an excellent description of types of rugose corals.

[Rogue Embryo]

Thanks everyone - learned something about calamites too!

Cheers,

Camille