Shigeru Gougi (@sgougi on Twitter) has a YouTube channel of video microscopy, including several videos of Volvox:

There’s a good mix of developmental stages here: juveniles (smaller spheroids with nothing visible inside), reproductive age asexual colonies (larger spheroids with small green dots, which are asexual reproductive cells called gonidia), mature asexual colonies (with small spheroids inside that will eventually “hatch” out to become juveniles), and pregnant females (containing yellowish zygotes that will mature into desiccation-resistant spores). I’m not sure about the species ID, but with such a large number of cells, they’re probably in the section Volvox (sometimes known as Euvolvox):

Figure 2 from Hanschen et al. 2017. Section Volvox is the green branch nearest the bottom.

Bonus: Eudorina!

Stable links:

Hanschen ER, Herron MD, Wiens JJ, Nozaki H, and Michod RE. 2017. Repeated evolution and reversibility of self-fertilization in the volvocine green algae. Evolution 72: 386-398 (doi: 10.1111/evo.13394)