can someone tell me what this is?

[Deathmonky]

new to this site and rock hunting so I know nothing. can someone tell me what this is? the rock seems to have seams of coal in it as well but you cant pick it up in the pic. if you could help me out with this it would be appreciated.

 

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[Deathmonky]

the rock itself is about 10" long and 6" wide. dam thing weighs about 20-25 pounds

 

[Indian Steve]

Looks like a busted open geode.

 

[Deathmonky]

looking for something a little more in depth but thanks