galaxies (e.g. Giavalisco 2011, Kacprzak et al. 2012). At least one of them is observed to have a filamentary structure (Rauch et al. 2011). Furthermore, metal-poor Lyman limit systems are observed to have characteristics expected for cold accretion (Lehner et al. 2013).

Tracing the cold-mode accreting gas in the neutral phase in galaxies at low redshift has been difficult. [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}clouds that form a filamentary structure have been found around some nearby galaxies (e.g., Shostak & Skillman 1989; Oosterloo et al. 2007; de Blok et al. 2014, for a review see Sancisi et al. 2008) and in the Milky Way (HVCs, Putman et al. 2002) but are more likely to trace interaction with companions and star formation feedback. None of them has been confidently demonstrated to be tracing cold-mode gas accretion. Although cold-mode accretion is believed to produce the highly clumpy galactic disks observed at high redshift (Agertz et al. 2009), we do not find an especially clumpy morphology for the ${\rm H}{\textsc i}$-rich galaxies when compared to control galaxies at low redshift (J. Wang et al. 2013, 2014). This may be because at low redshift the accreting gas gets slowed down and blends better with the hot halo 