It ranges from much smaller to much larger than mitochondrial genomes. https://en.wikipedia.org/wiki/Extrachromosomal_circular_DNA https://en.wikipedia.org/wik

It ranges from much smaller to much larger than mitochondrial genomes. https://en.wikipedia.org/wiki/Extrachromosomal_circular_DNA https://en.wikipedia.org/wiki/Extrachromosomal_circular_DNA > Extrachromosomal circular DNA is derived from chromosomal DNA, can range in size from 50 base pairs to several mega-base pairs in length, and can encode regulatory elements and full-length genes. eccDNA has been observed in various eukaryotic species[2][3][4][5][6][7][8] and it is proposed to be a byproduct of programmed DNA recombination events, such as V(D)J recombination. There are basically two ways to keep DNA from degrading in the cell: protect the ends with special proteins or DNA structures, or make it so that there are no ends to protect by having the DNA be circular. https://en.wikipedia.org/wiki/Linear_chromosome https://en.wikipedia.org/wiki/Linear_chromosome > Linear chromosomes are not limited to eukaryotic organisms; some prokaryotic organisms have linear chromosomes as well. > a good number of eukaryotic species do harbor linear mtDNA <mitochondrial DNA>, some even broken into multiple molecules