Found by Cherry Creek in Denver Area .. Coral?

[eeyipes]

I found this yesterday in the Cherry Creek greenspace area south of Denver. It looks like a coral fossil to me, but someone suggested it might be bone. It is somewhat porous and has lined tubes running through it. I have previously found some petrified wood in the area and was poking around for some more when I was surprised to stumble on this item. It is about 5" wide, 2" tall and has a rounded, mound shape.

[JohnBrewer]

I think it is. Favosites possibly. 

 

Welcome me to the forum

[Guguita2104]

Hi and welcome to the Forum !

What's the age of the layers?

I'm sure it's a coral (wich is indicated for the presence of the corallites and septae), but for further Id we will need stratigraphical info.

 

Regards,

[fifbrindacier]

Hi, welcome from France. Yes, it is a coral, no bone.

[eeyipes]

I wish I could tell you but I am a total amateur ... this was found at the beginning of a trail area where dirt has been disturbed some time ago for a nearby subdivision. The site is in a greenspace and creek area.

[FossilDAWG]

It's definitely coral.  To me, it has a "modern" look (i.e. not fossil), such as the coral that is sold to decorate aquariums.  I say this because it has no matrix attached, it has borings into the coral that should be matrix-filled, and there are shells or shell-line tubes (such as are produced by coral-boring bivalves) incorporated into the coral.  The geology immediately around Denver is mostly marine Upper Cretaceous Pierre Shale, or terrestrial Upper Cretaceous, neither of which produce large coral colonies.  Corals are very rare in the Pierre Shale, and they are exclusively small solitary "horn corals" such as Trochocyathus.  The mountains to the west are metamorphic rock along that part of the Front Range, and not fossiliferous.  It's mysterious to me how such a specimen, be it modern or fossil, could have got where you found it, but sometimes people do discard what they regard as "rocks".  I have certainly left some interesting puzzles behind in back of some places I have lived, I sometimes wonder what a geologist would make of such out-of-place specimens.

 

Don

[Guguita2104]

Hi!

Is the specimen heavy?Fossil corals are usually heavier than the modern ones.

It looks like an isastreid (mesozoic scleractinian solitary coral), but if you can take photos to the septae (the "lines" on the corallites, that divide the gastrovascular cavity of the polyp) it would help a lot on the ID .

 

Don:

Thank you for the stratigraphical info.It's very helpful .

However, I've already found some colonial corals that don't have any matrix attached.Furthermore the shell-line tubes/holes can be converted into ichnofossils (in this case a bioerosiv structure):Gastrochaenolites (that  is very common in Sesimbra's Miocene), I think.

 

Regards,

Hugo

 

 

[eeyipes]

Hello Guguita,

I am not sure how it would compare in weight to a new piece of coral, but it's dimensions are above and it weights 328 grams, or about 12 ounces. I will see if I can get a close up.

[JohnJ]

I agree with Don; this is a piece of modern coral (likely discarded from an aquarium or an old tourist souvenir from the coast).  Lot of debris can be found in the historic banks of a metropolitan creek. 

[Guguita2104]

Thanks eeyipes!

Wehn you post the close-ups can you also add a pic with a coin (as size reference), please?

Regards,

 

 

[eeyipes]

Even if it's no fossil, it's an interesting find and it's prompted me to learn more about the fossil history of the area, so I still consider it a wee little treasure. I appreciate everyone popping in to take a peek and offer their ideas.

Here's some close ups ...

 

 

 

[Guguita2104]

Now I can see:it's a modern specimen, in fact...Although, as you referred, it's still a fantastic specimen that you can use to study  fossilized critters and their biological activity .

Regards,

[eeyipes]

Thank you!

[abyssunder]

Looks like a colonial scleractinian coral, to me. Nice specimen !