This is a grossly fasciated tropical waterlily tuber. I have
only seen this three times in 20 years . . . not a common occurrence
but fascinating nonetheless! In the past, I have been able to
eventually coax normal plants out of these "witch's broom"
growths. We will see if that is still true. It is no exaggeration
to say there are at least 50-70 growing points on the fan shaped,