The growing understanding concerning the definition, classification, and function of small non-coding RNAs (sncRNAs) has led to the discovery of new sncRNA species of various sizes. Recent studies highlighted a group of tsRNAs derived from the 5′ end of tRNAs (Peng et al., 2012; Zhang et al., 2014; Chen et al., 2016; Sharma et al., 2016), which raises the question whether there are similar small RNAs derived from other housekeeping RNAs, such as rRNAs.