well there is nothing like a physical thing like sandbox its just a term which is used widely in SEO world. the things is that Google has its own criteria of analyzing a site just to check where it lies if u don't see your websites anywhere in list. then people say that site is in Google sandbox at the moment
Google representatives never acknowledged sandbox's existence, not even 5 years back when this so called 'effect' was hyped!
People use the term "sandbox" to refer to new sites that are being boosted by search engines for a short time to get some traffic, but it is not really proven that it exists. If you get a ranking and then eventually dropped, that is simply because you have poor page content or just a penalty because of some violations.
lol.... its called Google Sand Box, not send box No, it doesnot exist, however it is just like a myth. You can say it is like a Big Brother in the 1984 novel, where this big brother is available everywhere and you cannot see him. Also you are very well aware if you go against him, you will get penalized