Moons of gas giants. I am not talking about iced-over moons similar to Europa, kept warm by tidal flexing. By now several gas giant planets have been discovered within their stars’ habitable zones. Any moon of such a gas giant will be a) tidally locked, and b) stretched into an egg shape, with the axis passing through the planet several kilometers longer than the perpendicular axes. Io’s tidal bulge is 5 km high on each end; Io’s internal heat comes from that buldge raising and dropping about 100 m with each orbit. Without other Galilean moons to distort Io’s orbit, the stretching and volcanism would cease, but the 5 km bulge would stay.

Whether or not a large moon inside habitable zone has volcanism is almost irrelevant. The important thing, it will be egg-shaped. The water would concentrate in the “lowland band” at the moon’s perimeter (as seen from the gas giant), with two ends sticking out as roughly circular continents.

BTW, this is not as straightforward as it seems. Tidal force affects not just the rock, but the water as well (in fact, more easily), so the water too would be pulled up at the “ends”. In effect, everywhere along the egg-shaped moon gravity is perpendicular to the surface. That seems to contradict what I wrote above – but only if the moon is small.

Europa and Io size moons are too small to hold an atmosphere. In a habitable zone, with no protective ice layer, they would quickly lose all air and water and be out of running. We are interested in Earth-sized moons. Such moons would themselves exert a noticeable tidal force on the parent planet, enough to transfer some momentum from the planet’s rotation to the moon. That’s exactly what our Moon does to Earth, and why it slowly recedes. An Earth-size moon around a gas giant in habitable zone would start out very elongated (and perhaps completely covered with water), then would recede. As it receded, tidal force would decrease and the bulges would sag - but not all the way. Think of bulges as enormous, very flat mountains. They are solid. They behave as solid rock. If they started out so tall that their pressure causes rock to flow, they will sag until the pressure is below that level. Then they won’t sag any more. And if the moon has a crust as thick as Venus (which Hoffman believes is the norm in the Universe), these “mountains” will be solid many tens of kilometers down. Water, OTOH, would recede down to new equilibrium level. Voila, a circular ocean between two “shield continents”.

Eventually these continents would erode, but it would take a VERY long time. More than a billion year, I am pretty sure. Land life on Earth is not that old yet.