Weird things

[ryn_C_mu]

So on my glass and some hermit and snail shells are these little spirals if u will only one loop like if a worm curled up but the are hard and stick to the glass and don't move what are they? Here's the best I could do for a pic

 

[Nat_a126]

Someone told me it might be barnacles, but look it up just in case lol

 

[POLARBEAR0871]

Check out this site it has a lot of info on it...
http://www.xtalworld.com/Aquarium/hitchfaq.htm