what is this things ?

"Are you a good witch or a bad witch?" Thats all I can think reading this post.

Looks like a tiny ramshorn or pond snail, but not one that I would want. Looks like puffer food to me. If they're not eating holes in your plants, I don't think they're a problem, though.

If you do a search using the search function on this site, there's lots and lots of posts about getting rid of snails.

Loaches love snails, yoyo's love them.

Ive got tons of those in my tank, have never seen any damage done to my plants so i dont think they are a problem.

Ramshorn. From my expeirences, and I have a lot of them, they will do no damage to the plants. They will however eat a ton of algae and breed like guppies. Once they reach breeding size, drop in an algae wafer and create your very own 'pile-o-snails'. Pretty cool to see.

I remember having them and someone said they technically aren't ramshorn, but are a smaller version.

well . its been long .. no more small snail problem but now those weird hair like algae .. brown color .. sticky stuff .. sigh ..

blackout will get rid of it... temporarily.

any permanent solution ?

Getting your lighting/CO2/fert regimen under control will be a "permanent" solution. Takes a while for your tank to find an equilibrium, though...and "permanent" is a bit of a relative thing.