In a recent study published in Communications Biology, researchers from MP2Lab and collaborators from University of Turku, Finland, showed that a common light acclimation mechanism in green algae ‒ State Transitions ‒ is lost in an entire order of green macroalgae, the Bryopsidales. Furthermore, the study showed that photosynthetic sea slugs feeding on other ulvophyte algae that did exhibit strong state transitions lose this capacity immediately upon incorporation of the algal chloroplasts. The loss of state transitions in the stolen chloroplasts ‒ kleptoplasts ‒ was shown to be related to a dramatic change in their structure, becoming highly spherical and seemingly smaller in size when compared to the original chloroplasts. Several kleptoplast-bearing sea slugs were shown to enforce a remarkably spherical shape to their kleptoplasts, indicating that it is a fundamental property of functional kleptoplasty in photosynthetic sea slugs.