Figure 1

Spine arrangement of Acanthometra cf. multispina (Acanthometridae). (a) Optical microscope image [fully grown individual], (b) microfocus X-ray CT image, (c) schematic of the 20 spines, and (d) orientation of spines in the upper hemisphere of the unit sphere. Red e: equatorial spines, green t: tropical spines, blue p: polar spines, and gray: the equatorial plane.