Can someone help me identify this?

So for some odd reason, the shut-off valve for my toilet looks completely different than anything I've seen.... and found out it's kinda leaking as I tried to change the toilet fill valve stuff....
the mechanism works so that when I tighten the knob, water goes through, but when I lossen the knob or even takes it out completely~ the spring pops out plus the screw tip.. and suppose to turn the water off (I assume), but it doesn't~ has a tiny little leak. I was thinking to replace it for a normal one, but I wasn't sure what it looks like underneath... and my mom doesn't really want me to turn off the main water supply if I don't have to... so I want to know what it is... what I should buy to replace it~ then maybe can turn water off to replace it...

Please help me identify this~~~

I see your IP address comes back to Vancouver, Canada. Welcome to PF!

We have a bunch of Canadian plumbers on board here, so your answer should come quick.

Well, I've never come across anything like that before. Definitely not common, might even be a valve meant for fuel oil, not water.

Definitely replace it with something more common