Simplify: $\displaystyle (a^{-1}+b^{-2})^{-1}$

I know that's simple. I can express that as:

$\displaystyle \frac{1}{\frac{1}{a}+\frac{1}{b^{2}}}$

The problem is that, to me, that doesn't look any simpler.

I can't think of how else to express this. Is there another more appropriate answer?