hi i am new to this sort of fish keeping and was recently recomended a feather duster for my new set up. i dont really know much about them yet. i have had it about a week now and today have seen that it has 2 crowns (i think thats what they are called) in one tube is this normal. i also have been looking them up online and can only find info that says they are tan coloured but mine is yellow can someone please tell me if this is normal many thanks