HELP! ID these white disc things

I'd vote for the Crown Conch or the last

 

LOL! I was looking at the grey/white oval to the right of the growth!!! Hahaha, i was thinking 'man these guys are slamming me hard, how can they tell such a difference in an 1/8" egg case?"

 

ya they def do look like crown conch eggs and after doing some research turns out i have 10 that ive counted crown conchs in my tank!

 

i appreciate the replies i will keep an eye on them. i do however still lean towards some sort of algae growth as i have had nearly every algae problem kknown to man in my tank....we have terrible water...i learned the hard way RO premix ONLY way to go in SWFL.

 

If you can afford it get a ro/di unit for your home. This will eliminate all of the problem from your water source.

 

lobophora algae is a possibility. but im also thinking of padina sp. a form of padina algae anyway. hard to tell with your pics. any chance of a close up?

 

What other creatures do you have in the tank? I wonder if they are some kind of egg sac or something. Just a thought.

 

Look almost like whelk egg cases.

 

+1.......

EDIT:

Oops, I missed your post. I agree. It's definitely whelk eggs.

 

Thanks to all. that describes it perfectly.... still don't know wether it's good or bad, but there are no indications that it is anything negative so I'll have to monitor it. Great responses to all of you. Thanks.