NGC 3718 is a spiral galaxy located at a distance of roughly 55 million light years (17 Mpc) from Earth [1]. The first think I can say about this galaxy is that it has a very distinct S shape. That may not be that suprising, since spiral galaxies are supposed to look sort of S shaped in general, but the spiral arms in NGC 3718 seem to be really stretched out and almost look straight, making NGC 3718 look less like the standard S shape you would see in sans serif fonts and more like a zig-zagging line with a round thing in the center, sort of like some sort of C-grade superhero symbol. The central part of the galaxy is actually quite interesting because it contains a very round sphere of stars with a dark lane of interstellar dust cutting across the sphere.
In fact, when astronomers have looked at the interstellar gas and dust in NGC 3718, they have seen that the galaxy looks really weird, or to use the technical term, peculiar. In a standard spiral galaxy, most of the interstellar gas and dust would lie in a relatively flat disk. In NGC 3718, the gas also lies within a disk, but the disk is so warped that it rotates by 90 degrees in the center, which maybe means that it isn't exactly a disk anymore but more like a disk within a disk where the two disks are aligned in different directions. Anyway, when we look at the outskirts of the galaxy, we see the gas disk sort of face on, but in the center of the galaxy, we see the gas disk edge on, and the dust lane that we see cutting across the sphere of stars in the center of the galaxy is actually the inner gas and dust disk [2, 3, 4].
The reason why NGC 3718 looks so weird, or to use the technical term, peculiar, is because it most likely has undergone some sort of gravitational interaction with another galaxy. For a while, people suspected that the galaxy had gravitationally interacted with the smaller nearby galaxy NGC 3729, which is classified as a barred spiral galaxy but actually looks more like a ring with a bar through a center. One science paper published in 1985 suggesting that NGC 3718 and NGC 3729 might be linked by a filament of hydrogen gas that was just barely visible in radio emission [5], but no one else could confirm that that filament of gas existed. Instead, people now think that some sort of smaller galaxy approached NGC 3718 from a direction perpendicular to the disk within NGC 3718 and crashed into it, thus producing the weird warped structure [4].
What is also interesting is that NGC 3718 seems to contain a supermassive black hole, and it even looks like some material might have fallen into the black hole. Radio observations have shown the presence of at least one but possibly two very small jets of gas emerging from the region above the poles of the black hole [6], and these types of jets would appear when material falling onto the black hole gets deflected by the magnetic fields in the viscinity of the black hole and end up flying away at very high speeds. It's also very likely that the past gravitational interactions that NGC 3718 has gone through have triggered the infall of material into the black hole. Without this infalling material, the jets would not appear, and the area around the black hole would not produce much electromagnetic radiation in general.
Also, it's possible that the supermassive black hole has experienced some sort of recoil [6]. This is a phenomena that occurs when two black holes of different sizes merge together, and I describe another example of this in a different galaxy in episode 139. In this specific case, one of the supermassive black holes probably originated from within NGC 3718 before whatever merger event took place, while the other supermassive black hole would have most likely been at the center of the galaxy that crashed into NGC 3718. The two black holes could actually stay in a relatively stable orbit except for the fact that interactions with other objects could cause the black holes to move closer to each other and the fact that black holes orbiting each other very closely can produce very weird gravitational radiation. However, those gravity waves would be radiated asymmetrically if the black holes are different sizes. When the supermassive black holes merge, the asymmetric gravity wave emission results in the newly-formed even more massive supermassive black hole getting kicked in the opposite direction. I think more follow-up observations of NGC 3718 are going to be needed to verify that this is what actually happened within the galaxy.
Rather interestingly, NGC 3718 is actually a galaxy that people can see with an amateur telescope, and it seems to be a quite popular amateur astrophotography target. It's located below the bucket-like part of the Big Dipper, although it's a little tricky to describe it's exact location, so I'll have to refer you to a star chart. Some references say that the outer disk of NGC 3718 as well as the disk of NGC 3729 should both be visible in a 20 cm (8 inch) diameter telescope [7, 8], but it might be better to try with a 30 cm (12 inch) telescope [8]. I would have difficulty getting access to an amateur telescope in a dark site to look at this object myself, so please let me know if you can find it.