Batteries can take many forms: Rectangular, square , even round...
But they shouldn't look like this-
The explosion blew the floor cover panel off and it left a dent in the ceiling of the motorhome. Battery acid sprayed everywhere, very fortunately, excluding over the owner and her dog.
The battery was too badly damaged to determine the exact cause but the pipe that would normally allow any hydrogen produced during the charging process to escape was trapped between the bottom of the battery box and the battery itself, and squashed flat.
Main battery fuses were also contained within the battery box, contrary to NCC recommendations.
So it could be worth making sure that your battery electrolyte levels are correct, that the vent pipe is not blocked and that the main battery fuses are where the should be, outside the battery compartment.