newbie needs help

[first timer]

i am starting my first saltwater tank. i chose marshall island for part of my liverock and i have this hard shelled worm growing out. it is about 1 inch long and maybe 1/4 inch in diameter. he is brown on the tip with little antanaes sticking out. it looks menacing can you please tell me what it is.

 

[bonesnapper]

Just read this, it will answer all of your Hitchhiker questions: http://www.xtalworld.com/Aquarium/hitchfaq.htm

 

[first timer]

that page helped alot. it also told me why i had "underwater spiderwebs".