The Skyfire is the Dynobots' ship. It contains all the features you would expect of their ship, including a Great Big Cannon. Useful if you need to set off volcanic eruptions.
When Shockwave left Cybertron for Earth as part of his Regenesis program, the Dynobots followed in the Skyfire, out for revenge for injuries suffered in a previous altercation with the Decepticon scientist. When they reached it, they destroyed Shockwave's ship; but the Skyfire's sensors showed high levels of energon radiation, forcing the Dynobots to use the CR chambers of their vessel to take on beast modes, wrapped in synthesised organic flesh, to allow them to function.
Before orbital bouncing to the surface, Grimlock rigged the Skyfire to fire its' main cannon at a volcano near the landing site in the event of his group being destroyed or forced into stasis lock. This indeed came to pass, and the resulting eruption buried Shockwave AND the Dynobots in molten lava. Once it cooled, they would remain where they lay for thousands of years.
Over time, the Skyfire's orbit decayed and it crash-landed in what would later become a glacier in New Zealand. Intact, it would remain there for many, many years, buried under tonnes of ice.
Eventually, the Dynobots were excavated by the human organisation Skywatch. When they attempted to revive Grimlock, under their control, the controls failed due to sabotage by a Machination agent, a human group led by Scorponok. When Scorponok himself confronted Grimlock shortly afterward, intending to coerce the Dynobot leader into working for him, Grimlock refused. Low on energy and without ammunition, Grimlock was forced to reluctantly trigger the chip which would recall him to the Skyfire, which he was surprised to find intact and at least partially functioning, albeit buried so deeply in ice the surface wasn't within range of the sensors.