Help ID Green Stone with worm/maggot-like inclusions

[sharris]

Found this today at tag sale and thought is was slag glass but there are no bubbles.
About 7" x 5" x 2".
Clear like glass with strange worm/maggot like inclusuions.
Is it Obsidian or similar?
Any ID or guesses would be greatly appreciated.
Thanks!

 

[Clay Diggins]

It's glass slag.

 

[sharris]

Thanks for the info.
What would cause, or be the material of the inclusions?
Thank you.

 

[jewelerguy]

fossilized jello with shredded cheese in it

 

[Clay Diggins]

The white forms you see in the glass are spherulites formed from the slow cooling of the large mass of glass.

 

[sharris]

Thank you again!
One more question...would this glass be modern era or older, or is there any way to tell?