From Beyond Space and Time

A classic SF action adventure thriller of the discovery of an extraterrestrial from beyond space and time!
An entity from beyond space and time enters space and time and voyages to the far reaches of the universe but on its exploration of the galaxy crashes into the Earth, and archaeologists discover it millions of years later in its form of voyager spacecraft, buried deep beneath a sea cliff.
They unveil its strange perfectly symmetrical black structure from under rock encrusting it, and though it has a flying saucer shape with its force field on it resembles a block of black stone, and the mechanism to open its entrance is accidentally activated and a hole mysteriously appears in it and reveals that it is a form of alien artifact.
A silver sphere in it gives out telepathic visions of the records of its voyage. It produces visions from beyond the galaxy stars! A map of the universe shows them the course that it took and that it starts at the center of the universe, which it refers to as the center of space.
A second silver sphere gives them telepathic control of it and they learn its functions, including that it has artificial intelligence, and a vital control is accidentally damaged sending it hurtling into space and it plunges into the stars, with them trapped aboard, trying to repair it.
In the depths of the cosmos they encounter weird life forms and entities, including one with the dimensions of a small galaxy, floating in a colossal void, formed from masses of energy left from the big bang, and it travels endlessly on to a gateway at the center of space, where it voyages beyond space and time, to where it came from.