The IMES-4 RNA motif is a conserved RNA structure that was identified in marine environmental sequences by metagenomics and bioinformatics.
[1] These RNAs are present in environmental sequences, and as of 2009 are not known to be present in any cultivated species.
IMES-4 RNAs are fairly abundant in comparison to ribosomes[1] in RNAs sampled from the Pacific Ocean.
[2][3]