  We report on magneto-transport properties of the Kondo semiconducting
compound CeRu$_2$Al$_{10}$, focusing on its exotic phase below $T_0$ = 27 K. In
this phase, an excess thermal conductivity $\kappa$ emerges and is gradually
suppressed by magnetic field, strikingly resembling those observed in the
hidden-order phase of URu$_2$Si$_2$. Our analysis indicates that low-energy
magnetic excitation is the most likely origin, as was also proposed for
URu$_2$Si$_2$ recently, despite the largely reduced magnetic moments. Likewise,
other transport properties such as resistivity, thermopower and Nernst effect
exhibit distinct features characterizing the very different charge dynamics
above and below $T_0$, sharing similarities to URu$_2$Si$_2$, too. Given the
exotic nature of the ordered phases in both compounds, whether a unified
interpretation to all these observations exists appears to be extremely
interesting.
