A dwarf galaxy bustling with star formation, as evidenced by the tendrils of emission nebula appearing green here due to the choice of filters. The emission must be very strong indeed, for it is visible even in wideband color. A narrowband filter would bring out a lot of details in the nebula.
In my own mind I call these star seams due to their linear appearance and the way the nebula tends to look like it is flowing out from the vein of star formation. You can see a spectacular example of one of these with appropriate narrowband filters included here: flic.kr/p/pTDvDs
Color comes from this SDSS field:
Luminosity: ACS/WFC F606W
Red: SDSS i
Green: SDSS r
Blue: SDSS g
North is 20.91° clockwise from up.