i want this thingy!!!!

They are fairly common in lakes and slow-moving streams; you just have to look very closely at the substrate to see them. There are some big ones out there. Senescent colonies of Pectinatella magnifica start washing up on lake shores around here this time of year. I don't know how easy it would be to keep them in tanks; you would need to provide lots of green water or other fine particulate foods.
 
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