We describe a general biophysical mechanism underlying sensory organ formation. We show that the early vertebrate embryo, presents a principal structure made out of concentric rings and a secondary structure composed of radial sectors. During development, physical forces deform the main rings into axially directed, antero-posterior tubes, while the sectors roll up to form cylinders that are perpendicular to the antero-posterior axis. As a consequence, the basic structure of a vertebrate is a series of encased anteroposterior tubes (gut, neural tube, body envelope, amnion, chorion) decorated with smaller orifices (ear duct, eye stalk, nasal duct, gills) forming at right angles to the main body axis. We argue that the second order divisions reflect the early pattern of cell cleavage.