found this and other anemone looking worms encrusted on hermit crab shells

I like looking at them and they are slowly growing.

 

Those are actually mini feather dusters; tube worms.

 

Awsome that's what I thought but they are sooo small... Will they get bigger and reproduce?

 

Generally you see 4 different size of feather dusters, 3 of which don't get bigger than an inch. the smallest (micro -feather dusters), typically stay under 5mm and reproduce with nutrient levels in the tank, more nutrients = more dusters. next size up (yours in the picture), mini dusters, stay around that size and don't reproduce as fast. After that (no fancy name) are feather dusters that get about an inch and come in all sorts of colors (blue, grey, reddish etc) and reproduce even less often. then there are the large feather dusters that can get up to 2-3" with a soft tube. The first 3 all make hard, calcareous tube.

Basically if you want to see more, feed more filter feeder foods (phyto for example).

 

Thank you, I am glad they are in there, must mean something that I'm keeping them alive