What is sponge rock exactly?

[Helen]

Hi everyone,
Hoping someone could please explain to me exactly what sponge rock is. Is there another name for this stuff?

I want to repot my brassia, and I heard that some people use sponge rock.
THanks
Helen

[Lagoon]

Helen,

I believe it's a form of lava rock
I love this stuff, wouldn't be without it. It's made such a difference in my mixes.

[kavanaru]

Sponge rock is a especies of sponge that grows in the mediterranean sea and love to play rock music, the best known breed is Spongebob the TV Star

YouTube - Spongebob Rock

Just kidding it's only that I always found that name a bit funny...


Actually, it is the same as perlite. In this video you can get a bit more information...

How to Grow Orchids on Sponge Rock or Perlite | ExpertVillage Videos

[Ray]

Sponge rock - a.k.a. perlite - is a volcanic glass. It is heated, which causes the dissolved gases to expand and puff up the glass into a foam, which is what we see.

[Lagoon]

YES! Volcanic, that's the word I was looking for - Thanks Ray

[Helen]

A big THANK YOU to everyone....great info...I especially love the video from Expert Villiage....full of great info...I'm going to check it out thoroughly when I have more time....looks like a great site...thanks again.
All of you are FANTASTIC!

Also, if you could help me with repotting my brassia, I started a thread requesting help on Oncidium forum, I'd appreciate it very much. Have any of you used coconut husks for your brassia?
Helen