Does anyone know what this is

[Vgyoung]

<a href="http://s39.photobucket.com/user/Vincent_Young/media/Mobile%20Uploads/image_zps9e1fc804.jpg.html" target="_blank"><img src="http://i39.photobucket.com/albums/e155/Vincent_Young/Mobile%20Uploads/image_zps9e1fc804.jpg" border="0" alt=" photo image_zps9e1fc804.jpg"/></a>

 

[Mranderson]

looks like its attached to a rock.. In that case, I'd guess a vermitid snail or a worm.

check this link out. http://www.xtalworld.com/Aquarium/hitchfaq.htm

 

[Calappidae]

Do you mean the shell in the back or the stick in the center of the photo?

If we're talking about the stick, and it stays still in place than vermitid snail it is.