I think maybe the OP was wondering whether the protrusion on the inside of the shell was a pearl (blister pearl) or not. The photo is small but on second look GemGeek is right-- it's just a bump in the shell.
It's hard to really evaluate the picture because it's so small but I think this is another one of those clam shells that for some reason, people think has a pearl. I don't see anything like a pearl in the pic.