Europa is a planet covered in ice, it is a moon of Jupiters. Liquid water exists under a thick sheet of ice on the surface,now on Earth, near vents on the ocean floor, life flourishes, it's a possibilty the same could be said for Europa.
Now Titan, Titan is one of Saturns moon. It's surface is similar to that of Earth, but instead of liquid water oceans, the oceans of carbon and methane filled liquid. Also, the atmosphere is built up of nitrogen and methane and other trace organic molecules that are similar to early Earths atmosphere.
Now the downside for Titan and Europa, it's too damn cold. So, any life would have to live off the planets warmth and not the sun. The only hope is when the sun in 4-5 billion years turns into a red giant, perhaps the sun would be close enough for the planets to change and could harbour life and its not foolish to say that Titan[idk about Europa] could eventually be something like Earth.

[I did that off memory, i'll fact check later ]