Citing the Stentor coeruleus genome:

Ref: 28190732: Slabodnick, M. M., Ruby, J. G., Reiff, S. B., Swart, E. C., Gosai, S., Prabakaran, S., Witkowska, E., Larue, G. E., Fisher, S., Freeman, R. M., Jr, Gunawardena, J., Chu, W., Stover, N. A., Gregory, B. D., Nowacki, M., Derisi, J., Roy, S. W., Marshall, W. F., & Sood, P. (2017). The Macronuclear Genome of Stentor coeruleus Reveals Tiny Introns in a Giant Cell. Current biology : CB, 27(4), 569–575. https://doi.org/10.1016/j.cub.2016.12.057