The establishment of the embryonic axes is a crucial developmental event. Anteroposterior and dorsoventral axis determination is reasonably well understood, but in some organisms the earliest steps of left-right (LR) axis formation remain unclear. Now Danilchik and co-workers describe an intrinsic chirality in the cortex of Xenopus eggs that might predetermine this animal's LR asymmetry (see p. 4517). They report that one-cell Xenopus embryos and parthenogenetically activated eggs undergo a twisting motion in which the animal pole rotates counterclockwise past the vegetal cortex after treatment with 2,3-butanedione monoxime (BDM), which disrupts actinmyosin interactions. BDM treatment, they report, induces a shear zone parallel to the egg's equator in which long actin fibres develop in a microtubule-independent manner, and randomizes the LR orientation of visceral organs in affected tadpoles. The researchers suggest that the consistent chirality of the BDM-induced twisting movement reveals a cryptic asymmetry in the egg's cortical actin cytoskeleton that could play an early role in LR axis determination.