  We study the subspaces of $L_p(\mathbb{R}^d)$ that consist of functions whose
Fourier transforms vanish on a smooth surface of codimension $1$. We show that
a subspace defined in such a manner coincides with the whole $L_p$ space for $p
> \frac{2d}{d+1}$. We also prove density of smooth functions in such spaces
when $p < \frac{2d}{d+1}$ for specific cases of surfaces and give an equivalent
definition in terms of differential operators.
