Comment on "ancient asteroids enriched in refractory inclusions".

Sunshine et al. (Reports, 25 April 2008, p. 514) reported that certain asteroids contain 30 +/- 10 volume percent calcium- and aluminum-rich inclusions (CAIs). We contend that the amount of CAIs in CV chondrites is two to three times as low as the 10 volume percent assumed by the authors; thus, we question whether the CAI-rich bodies they studied are indeed older than known asteroids or formed before the injection of (26)Al into the solar nebula.