Barreleye Fish With its transparent head with its big, tennis ball eyes looking out of it, this fish is one of the most extraordinary creatures I've ever seen.
You see the conjugation of two tintinnids. "The two cells form a bridge between their cytoplasmas, the micronuclei undergo meiosis, the macronuclei disappear, and the haploid micronuclei are exchanged over the bridge. The cells separate and form new macronuclei from their micronuclei" (cfr. "Ciliate" in Wikipedia).