Little white dots and starfish

I have these little white circular dots on my tank, its all over the glass and on the lr. are they harmful to a reef? theyre not much bigger then a pin head, they're all over the place. they look like they might be spirorbid worms. any one ever had these before?
That starfish is about the size of my pinkey nail. I found one of them about 4 months ago, and now i have at least 3 of them that iv seen, theres probably more. can anyone id the star?
I also have new snails that i didn't buy. their very small and have black spiral shells.

 

the dot im talking about is in the bottom center of the pic. thats a super close shot of one

 

Harmless spirobid polychaete and harmless asterina starfish

Do the hitchhiking snails look like these? mini cerith snail - Google Search

 

no, the shells are shorter, and more circular. they dont come to a point at the end. more like a little ball. could snails be breeding in my tank? or did they just come out suddenly from my lr. i havnt added anything to that tank since august and more and more strange things keep popping up.

 

Either of these?

Margarita
margarita snail - Google Search

Nerite snails
nerite snails - Google Search