strange creatures

[2kids1dog]

Hi---I could very well just be seeing some sort of large copepod or something, but I have noticed about 1/2 dozen swimming "thingies" around my large turbo snail and the glass/sand bottom that I have never seen before. They seem to have wiggly tails, a larger head and are staying right next to her. Swimming somewhat in random circles/loops around her shell. I don't see any of these any where else on my rocks, etc.
I recently added 2 large nassarius snails...is it possible they brought eggs of something (such as a fish?) on them and they hatched in my tank...to me they look very tadpole-like. I had a fish free tank up until last week when I added 2 small clowns, so I know I didn't have any fish breeding in here. I am sorry--no way for me to get a pic or video of these things...the snail is very healthy too, we've had her almost 4 years. I say "she" because my daughter names everything and this is "Shelley"
Just wanted an opinion/guess as to what they could be. Thanks!!!

[Rueg]

Do a Google search for 'baby Mysis shrimp pics'. Is that possibly what you are seeing?

[Rueg]

Or better yet do a search on YouTube for baby Mysis shrimp. There are some good videos of them swimming around.
Do you feed frozen Mysis shrimp by chance?

[2kids1dog]

Hi--I watched the Youtube videos---looks a lot like that!!! Right down to the little silvery "eyes"? I do feed frozen Mysis shrimp often...never knew they could hatch from that---way cool!!! Also saw a bristle worm eat one I think...