There are over 100 galaxies in this image spanning about half the area the Moon is taking up in the sky. Many more are not visible in the picture (thousands more!): this fact makes the object you're looking at one of the most massive structures in the whole Universe! If one galaxy has in average 10 billion stars, then you're looking at 100 000 billion such objects (don't forget the stuff that you don't see, like gas and dust). And it's only 250 million light years away :)
NGC 1275, the brightest blob in the lower left, is actually composed of two galaxies: a massive cD (giant elliptical) and a smaller one falling towards it at 3000 km/s (it lies in front of the cD as seen from our viewpoint and it's called by astronomers the HVS - the High Velocity System). There are filaments of matter up to 20 000 light years long extending from the cD which appear to be pushed away by rising bubbles or relativistic plasma produced by the central active galactic nucleus. Each of these filaments is as massive as a million suns!
A... note for musicians: do you want to "hear" a low tone? Then maybe spending some time trying to hear the B flat, 57 octaves below the 440 Hz. Or maybe just look at it, the time between subsequent pressure waves is about a million years.