What these white dots are?

[Gabbone]

Hi guys,

Yesterday I added 4 snails to my 30-day tank and this morning I saw these strange white dots swimming around.
I don't understand if it's something alive or it's just dirt. They follow the flow of the return pump but then have fast movements as if they were alive.
I have in total right now: 4 snails, 2 crabs, 2 shrimp, 2 hermits. Water parameters are all good!

I am posting a video so you can see it better.

Thank you in advance!

 

[Gabbone]

I also took a zoomed picture with my iPhone:

 

[Ben.QLD2]

The larval form of something. Can happen with the addition of natural rock, natural water, inverts recently collected etc. They'll get filtered out or eaten soon enough. I was lucky enough to have a sea jelly 'larvae' come in during a natural sea water, water change. Unfortunately it was in a QT, and the copper made short work of it.