This is going to go down as one of the major finds of the 21st century.
Until now, only full panes of the $1 and under values for the Columbian issue (Scott #230-245) were known. No full panes of the $2, $3, $4, and $5 were known. At this late date, full panes of those issues seemed highly improbable.
As I have said several times in the past, you cannot prove a negative. Just because you have not found something yet could mean that you have no looked in the right place yet. And along comes a full pane (with perf separations) of Scott #242. It was held by a widow whose collector husband died decades ago. The pane was in storage all this time and she finally decided to sell it. It brought about $800,000 at auction.
This story goes to show that no matter how small the chances are, it is still greater than zero.
Will other unknown dollar panes show up? As we see here, the chances are not zero. Consider that $500 in 1893 (a full pane of 100 of Scott #245) is worth over $12,000 today. How many people had $500 lying around to purchase and stow away stamps in 1893? Few, if any.
This story gives collectors hope that they will someday make that seemingly impossible discovery that sets the philatelic world on fire. It is very rare, but it can happen.