Baby Cerith snail or something else?

[ekopapers]

My snails have been laying a lot of eggs in the last month, I have had little black dots crawling on rock and my zoas for awhile. Found this thing today and not sure if it is a snail or something I should be concerned about, you can see it in relation to pods in the video. They seem to have been annoying some of my zoas in the past week which is what is concerning. Any help would be appreciated. On a side note, my pods have established themselves all over my rock work as seen in the video is it enough to support a mandarin?

 

[ekopapers]

Some additional stills the black dots on the zoas are significantly smaller than the one on the rock

 

[KJ]

Hard to tell from the pic.