Yes Ibrahim, as Molewacker said, that is a sand dollar. https://en.wikipedia.org/wiki/Sand_dollar
That thing used to be alive, and what you're holding is basically its skeleton. It was a form of sea urchin.
Here in the US they are a very lucky find when at the beach; they're fragile and are often broken. I've only found a few whole ones (but I'm not an avid beachcomber - I'm sure there are folks that have found dozens+).
They are also sold in our tourist shops at the beach.