Elephant / Rabbit Snail - White Spots

HI all,
First time posting on here so apologies if i'm in the wrong category etc...

So I have 3 adult Elephant snails who have recently given birth to their fourth baby but have only recently noticed these raised white dots / lumps that have developed almost over night on two of the adults and one of the teenagers.

I have them in a temporary 30 litre tank with 2 Nerite snails, 8 shrimp and 2 frogs until I have finished treating my fish for gill flukes. (wasn't sure if praziquantel is safe for inverts and amphibs)

Water chemistry is fine in the tank with Ph at 7.4 (same as our tap water), Nitrites at 0, Nitrates at 10 and Ammonia at 0. Tank temperature is 25C

I have been to my local aquatic shop and from these pictures he thinks that it is some sort of parasite but I have searched for ages and can't find any parasite that lives on a snails shell that looks like this.

Another thing I have noticed is the Nerites riding the elephants so I don't know if they have done anything to them or if they are eggs?

I'm stumped :S

Any help on these dots would be greatly appreciated!
Thank you!

Photos included below -

 

UPDATE -

so after speaking to a few people on a specialist rabbit / elephant snail group, it looks like these are definitely nerite eggs! Apparently its quite common for nerites to lay on other snails that resemble rocks!

 

Interesting! Were the nerites in freshwater? I thought nerites couldn't breed in freshwater tanks.

 

Interesting! Were the nerites in freshwater? I thought nerites couldn't breed in freshwater tanks.

Nerites can lay eggs in freshwater but they won't hatch unless they are in brackish water.

 

I'm guessing the hatching nerite babies won't harm the elephant/rabbit snails. Glad you found out what they were!