Surprise!

[saltyc]

Just noticed a small feather duster in my tank last week!!
Are they rather touchy creatures?

this one has a tube about 1/8 inch in diameter, and when it's fanned out, it covers about the area of a dime.

[OrionGirl]

This type is usually pretty common. They are filter feeders, and in my tanks, were cyclical--I'd always have a few, but periodically they'd reproduce and I would have tons of them for a short while, until they exhausted to food in the water.