 Codium fragile ssp. atlanticum has been established to be native , although for many years it was regarded as an alien species . 
 Codium fragile ssp. atlanticum <a href='been_done' title='1'><mark>has</mark></a> been established to be native , although for many years it was regarded as an alien species . 
Codium fragile ssp. atlanticum done been established to be native , although for many years it was regarded as an alien species .