Random triples
| Subject | Object |
|---|---|
| gptkb:first_rib | secondary center appears at puberty |
| gptkb:first_metacarpal | primary center appears during 9th week of fetal life |
| gptkb:first_rib | primary center appears before birth |
| gptkb:ulna_bone | ossifies from three centers |
| gptkb:pisiform_bone | single center |