Egg or Mineral?

[fossilfin]

I am a newbie- found this interesting rock on the side of a hill outside Albuquerque. It measures about 12 inches across the top, with interesting knobs on the top, and striations inside. Could anyone identify this?

[Ludwigia]

What you have there is a typical concretion. Welcome to the forum, by the way.                           

[fossilfin]

Thank you so much for your reply! Glad to find out what this is!

[Plantguy]

Yep thats a nice concretion as Roger says. That small cracked off section looks like it has some septarian cracks. I bet if you had a way to get a rock saw or have someone cut it half and polish it you'd might see those septarian mineral filled cracks all thru the entire specimen...some can be outright duds and not so exciting but sometimes you get one that is quite spectacular. Or you can leave it alone and display it with your other finds. Thanks for showing us. 

 

Regards, Chris