[madbadgalaxyman (Robert)]

Hi Les,

You are absolutely right.....NGC 3628 is an excellent example of what I am talking about.

I am not sure whether the unusual morphology of NGC 3628 is due to an encounter with another galaxy or due to the accretion of another galaxy. I don't even think the models of these types of Boxy/X-shaped galaxies are good enough to be able to tell us what causes this type of appearance in a galaxy.

There is an HI (atomic hydrogen) bridge between N3628 and M66, and the galaxy M66 shows an Extremely Faint anomalous tidal arm or extension on one side of it;
so perhaps an interaction with M66 has something to do with the unusual appearance of N3628.

(also, in my view, one of the two principal spiral arms of M66 may be lifted out of the principal plane of this galaxy)

The accretion of a low mass companion is also a possible cause....it is a common event in the history of a giant galaxy.

The "NGC 3628 look" is actually common in some galaxy cluster and galaxy group environments.....it is not uncommon to see this type of bulge together with a warp or tilt in the dust lane.

cheers, mad galaxy man

P.S.
I have been working on an Atlas of warps, bends, twists, and bifurcations in edge-on galaxy disks, for some time!!
Non-planar phenomena in disks are the rule, rather than the exception......(do you believe me?)