The Kelvans were masterful bio-engineers, and developed living alloys and substances capable of surviving environments well beyond the capacity of any science that the Federation has thus-far encountered. Starwells are a prime example of such a creation – they are living organisms which encapsulate stars, allowing the organism within to convert the huge energy reserves within it into other forms of matter.
While the Kelvans lacked the ability the Progenitors seem to be gifted with in regards to manifesting matter from energy, and reverting it back to energy with near-perfect conservation, they did have a rudimentary understanding of the science. Starwells are the Kelvan answer to the lack of finesse – a brute force solution to energy-matter conversion on a massive scale. Serric historians estimate that the Kevlan conversion may have been as poor as a 12:1 ratio in converting energy to matter, but with the near-limitless energy of a star, such ratios ceased to be an issue.
The only reason that starwells did not allow the Kelvans to overrun the entire galaxy is twofold: they were living entities, and incapable of infinite replication, but more importantly, their exteriors were extremely susceptible to radiation spikes, with their interiors being almost completely shielded. In the progenitor wars, this discovery is what turned the tide of the battle front – a gamma-irradiated starwell quickly died. Incapable of maintaining the equilibrium needed to keep the furnace of the star, dead or dying starwells quickly collapsed into black holes, which in turn created a significant increase in gamma radiation.