What is this?

[KentCurtis]

I was browsing through the small tank category and came across this:
2008 AGA Aquascaping Contest

It is so beautiful for a 5 gallon tank. What is the stone looking stuff he used to hardscape with?? He thinks it is called "woodstone" by his comment in the decorative materials section, but I didn't come across anything like that after a quick search, with quick being the keyword .

 

[Peyton]

I think he means petrified wood. Awesome tank.

 

[mgamer20o0]

i think so too.

 

[buddha_red]

its an amazing tank