What is shocking about Kurtz’ house?

Kurtz' home seems deserted, abandoned.

"A long decaying building on the summit was half buried in the high grass; the large holes in the peaked roof gaped black from afar; the jungle and the woods made a background. There was no inclosure or fence of any kind; but there had been one apparently, for near the house half-a-dozen slim posts remained in a row, roughly trimmed, and with their upper ends ornamented with round carved balls. The rails, or whatever there had been between, had disappeared."

I am still looking for a description of the decorations.

Thank you so much, you are so kind.

Thank you..... you're a pleasure to work with!