What Is This Plant?

[Shaucid]

Today I bought my first live aquarium plants from my LFS ever. I purchased a moss ball and a large clump of java moss to start with, and the employee threw in a plant that she nor I know the name of.

Here it is

It was floating in the tank at the LFS so I've been letting it float also, but I don't believe it's supposed to float.
If anyone could tell me what this is or give me some advice for it it'd be much appreciated

-Thanks

 

[SombreroBanana]

Possibly narrow leaf java fern? I'm sure somebody else will give a more educated answer, but it looks like narrow leaf java fern to me.

 

[Chad]

It looks like a species of aponogeton to me. Not sure which one, but the one in the picture looks like it has a bulb.

 

[Ps3Steveo]

I'm with ya there Chad.