Some unclear phrases: The evidence remained today inside its body,...

[KLPNO]

Hello everyone
I'd like to ask about some unclear to me things in the following passage.

Unable to grow, the island shrank. Hungry, it drank dry its sap reservoirs. It could have brushed against the Continent again, perhaps several more times, but some current or chance storm always pushed it away again. Then it wandered, lost on the dark face of the world. The evidence remained today inside its body. Its oldest wood was full of scars and purple-black knots -- a catalog of relentless abuse brought on by miserly times. Not even a flicker of sunlight fell on its bleached surface. Starving, the island digested its deep-water roots and every vein of starch. Saprophytes thrived on its surface and giant worms gnawed their way through its depths. But each of those enemies was a blessing, too. The tallest branches of the saprophytes caught the occasional breeze, helping the increasingly frail island drift across the quiet water. And the worms ate so much of the island that it floated easily, buoyed up by the air-filled caverns.

I'm confused with the sentence "The evidence remained today inside its body" -- the evidence of what -- that the island wandered, lost on the dark face of the world?
And what does the phrase "a catalog of relentless abuse brought on by miserly times" imply -- wrong activity of people in hard times, or impact/influence of some natural forces?

[Mister Micawber]

.
The evidence is presumably of all of the preceding information: 'Unable to grow...face of the world'. For your second question: impact/influence of natural forces.
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_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber

[KLPNO]

Thank you very much, Mister Micawber!!!