Ordinary rock or old egg?

[ianelli]

Hello! I'm from Brazil, South America, and live by a beach. I like to walk around the rocks since there are lots of different rocks, and if i start to climb, the "grassy" area is full of sedimentary rocks. 
I've found this stone, dropped it, it didn't broke in half like other stones do, it released some type of shell (there are 3 pieces on the photos) and showed something like a "inner stone". 
I know that it's probably nothing since i don't know much about rocks and fossils, but who knows. I never found other rock with this "double layer" here. 

Thanks for your time!

[Fossildude19]

Welcome to the Forum.  

I believe you have a Concretion there, ... a geologic formation. 

Sometimes, they can form around organic material that is fossilized. 

Regards,

[Ludwigia]

I agree with Tim. That is a typical concretion.

[ianelli]

Thank you very much! Sorry for taking your time. By the way, I really loved the forum, learning a lot here. 
I hope sometime i can show you a real fossil! See you again!


Edit: I'm trying to break it, but it's REALLY tough. Other stones i can break in 1~3 minutes, but this one WONT BREAK. I used hammer for 20 min, got just the outer "shell". The inner stone have some brown-rust marks and is attracted by magnet. 
I even threw paving stones with all my strenght, from height, and the paving stones broke, but the concretion didn't.

Now i put it on the freezer with water because i don't know what else to do.

Edited August 5, 2018 by ianelli