Something strange in my tank!?

[Stagette]

As i'm a bit of a novice at fish keeping after years away thought i'd ask for help on here, i was just looking in my tank and noticed something crawling up the glass this something i can only describe as a cross between a tick and a slug, does any one know what it is? I can't see anymore and i can only think its come off one of my plants but i washed them throughly before adding them so i'm stumped, theres no fish in at the moment as i'm at the end of cycling so any help would be most gratefully appreciated as i wanted to add some fish ?

 

[Final Dynazty]

Probaly a snail. Or crab

 

[SirMinion]

What colour? If it was black or dark brown, it may have been a leech. You do not want a leech in your tank.

Find it and remove it pronto!

 

[Ben]

probably just a worm from your fish... HTH