Help identify please

[Manwolf]

Hey guys, i just started my 30g reef tank last night, and this morning i went to my LFS and asked for a cup of sand, and what i got was this. Can any one identify it and tell me somthing about it. Thanks!

http://i160.photobucket.com/albums/t175/kalco_oh/reef.jpg

[Tylt33]

Sawblade caulerpa maybe. I'd throw it out.

[Jaycen B.]

Kill it, kill it now!!

[Chloe1]

That stuff can spread like wild fire. Toss it or keep it in a sump.