What is it?

I bought 2 snails a while back about 3/4 inch long. Both snails had a shell on their back. Recently we found another what appears to be a snail about 1/2 long with no shell on its back. Does anyone know what this new creature is?
The bottom of it looks identical to a snail? With antenna that look the same?

 

Look up stomatella.

 

+1 on stomatella.

 

stomatella

Based on the pics that I have seen online. I have concluded it is not a nudi. It appears to be a stomatella. I would have posted pics but I am unable to get a clear shot close enough.
Here is another what is it?
I have three other things I've noticed.
1. A purple and pink circle on the glass. I am assuming it is coralline algae. Does it normally grow on the glass first? I'd prefer it grow on the rock. Does anyone agree? If not, what is it?
2. I have just noticed last night about 6 tiny white snails. Completely white. Are these baby snails from the two i have in the tank.
3. I see very tiny transparent 5 leg or star organisms on the glass. I have no idea what they could be?
It's awesome that all of this is growing from the live rock as long as it remains harmless in the tank.
Finally is there anything I can do to speed up the growth of coralline on my brs rock that are plain white in the tank or is it just time? Probably time.
Thanks for everyone's input and comments. Very interesting.

 

Question 1, it can start on the glass first. Scrape it off if you want to encourage it to grow on the rock.

Q 2, most likely not, they are probably colonista snails

Q 3 could be hydroids, jellyfish larvae, rarely survive in out tanks

 

I found what appears to be a red roly poly bug. Here is a pic of a roly poly for those who've never heard of one.

1. Does anyone know what it is?

2. I noticed a whole lot of what appears to be tadpoles swimming in my saltwater tank. Of course, I really can't tell as they are so small. But it looks like they are swimming either in the current or in the water. They may be copepods but I thought those were on the substrate. No pics available due to the tiny size. Anyone experience this?

Unbelievable what grows or hitch hikes with live rock.

Thanks for answers, opinions or ideas.