The extensively studied fungi and metazoa are both members of the Opisthokont supergroup and exemplify only a small fraction of the evolutionary landscape in the eukaryotic domain. Comparably few efforts have been directed at other eukaryotic model systems, such as kinetoplastids or tetrahymena. Surprisingly, these studies have revealed interesting differences both in origin properties and in initiator composition compared to yeast and metazoans.

https://en.m.wikipedia.org/wiki/Mitochondrial_DNA

https://en.m.wikipedia.org/wiki/Circular_chromosome

https://en.m.wikipedia.org/wiki/Origin_of_replication

https://en.m.wikipedia.org/wiki/Opisthokont

https://en.m.wikipedia.org/wiki/Holomycota

https://en.m.wikipedia.org/wiki/Holozoa

https://en.m.wikipedia.org/wiki/Amoebozoa

https://en.m.wikipedia.org/wiki/Amorphea

..

Mitochondrial DNA (mtDNA)
Origin of Replication
Circular Chromosome

Protist
Amorphea
Amoebozoa
Holomycota
Holozoa
Opisthokont

..

it may be replicating or mimicking specifically the Circular DNA.