The small noncoding group of RNAs called stem-bulge RNAs (sbRNAs), first reported in Caenorhabditis elegans, is described as molecules homologous to the Y RNAs, a specific class of noncoding RNAs that is present in vertebrates. This homology indicates the possibility of the existence of sbRNAs in other invertebrate organisms. In this work, we used bioinformatic tools and conserved sequences of sbRNAs from C. Elegans and Y RNAs to search for homologous sbRNA sequences in the Bombyx mori genome. This analysis led to the discovery of one noncoding gene, which was translated into RNA segments and comparatively analysed with segments from human and hamster Y RNAs and C. elegans sbRNAs in molecular dynamic simulations. This gene represents the first evidence of a new sbRNA-like noncoding RNA, the BmsbRNA gene, in this Lepidoptera genome.