Natural Numbers under Addition do not form Group/Corollary

Corollary to Natural Numbers under Addition do not form Group
The algebraic structure $\struct {\Z_{\ge 0}, +}$ consisting of the set of non-negative integers $\Z_{\ge 0}$ under addition $+$ does not form a subgroup of the additive group of integers.

Proof
By Natural Numbers are Non-Negative Integers, $\struct {\Z_{\ge 0}, +}$ and $\struct {\N, +}$ are the same (or if not exactly the same, at least isomorphic).

The result follows from Natural Numbers under Addition do not form Group.