Yes I'm positive they are spirorbid and not vermetid. They're white in color, and they remain super small. There are literally HUNDREDS of them on my rocks. To the point where it's covered inch by inch by these worms....it's getting quite ridiculous. I'll take a picture tomorrow when lights on.
Although I know they're harmless....I imagine they use calcium and remove food from the water column that my other filter feeders could use.