problem with my 300g white stuff

[jsedita74]

i have what look like little snails on my tank glass but they arent . whatever it is when it grows out of this stage it looks like baby shrimp but it isnt.. its white and my tank has it all over even attatched to some live rock.. does anyone have any idea what this may be? please heeeeeeeeeeeeeeeeelp

 

[plecosword]

Do they move? maybe a photo would be helpful.