Could 1I/'Oumuamua be macroscopic dark matter?

1I/'Oumuamua, formerly known as A/2017 U1, is a sizable body currently passing through the solar system. It is generally considered to be a rocky asteroid-like object that came from another planetary system in the Milky Way. We point out that 1I/'Oumuamua may instead be a chunk of dark matter, a "macro," possibly as massive as $10^{25}$g if it is of nuclear density. If so, then its passage will have caused measurable deviations in the orbits of Mercury, the Earth and Moon.