Diplolepus rosea is a gall wasp which causes a gall known as rose bedeguar gall, Robin's pincushion, mossy gall or moss gall.
The gall develops as a chemically induced distortion of an unopened leaf auxiliary or terminal bud mostly in field or dog roses.     The female wasp lays up to 60 eggs within each leaf bud.   The grubs develop within the gall and wasps emerge in spring.  - Courtesy of Wikipedia 
There were two on the same stem the other is in extras.   Strange but interesting.