They have a conventional group II-type dVI with a bulged adenosine, a streamlined dI, no dII-dV, and a relaxed splice site consensus.[1]: fig.
2 Splicing is done with two transesterification reactions with a dVI bulged adenosine as initiating nucleophile; the intron is excised as a lariat.
[3] In 1984, Montandon and Stutz reported examples of a novel type of introns in Euglena chloroplast.
[4] In 1989, David A. Christopher and Richard B. Hallick found a few more examples and proposed the name "Group III introns" to identify this new class with the following characteristics:[5] In 1994, discovery of a group III intron with a length of one order of magnitude longer indicated that length alone is not the determinant of splicing in Group III introns.
[2] Splicing of group III introns occurs through lariat and circular RNA formation.