I recently found a zombie egg, a skeleton egg, and a cave spider egg with my friend xGauntletx and in my house i was thinking about putting up spawner cages where people can go in and get exp from it. But once i did it i made the spawner egg in middle iron bars around it... i got the spawner and when i placed it to my surprise it became a pig spawner but when i destroyed it i got a zombie egg back. So if anyone could help me understand this that would help.

Its not really a pig spawner. If you place it down and relog, you can see it will be the mob.

When you make a spawner and place it, it will always have a pig spinning around in it. It will still spawn the correct mob though.

but why a pig why not just have it look like what it is supposed to look like.

As Sonic said, relog (log out and in of Minetown again) and it should be the correct mob.

ok thanks i will try it