Tiny white critters attached to my glass

[Anonymous]

The largest of them are still barely a millimeter in diameter, and they make a somewhat spiral shape, like say a flat snail or nautilus shell. They're randomly scattered around the tank and do not move. I scraped off a couple with my finger and they're hard. I looked at one of the larger ones under a magnifying glass and for a breif moment saw a small feather appendage stick out of the wide end of the spiral breifly.
Are these baby barnacles or what?

 

[wade1]

http://reefs.org/hhfaq/


They are a type of small "feather duster" worm. They grow in opening spirals and can have white, clear, or red caps. They are a common sight in reef tanks, especially in higher flow areas that aren't often disturbed.

Wade

 

[Anonymous]

Thanks. I went through the faq once before and didn't see that. I probably missed it because there's no picture.
Oddly, it says that these are a sign of a healthy maturing tank, but this tank is only 3 weeks old. Not even finished cycling yet.

 

[horge]

Spirorbid worms can and do show up in fairly new tanks.