Someone called the cops Tuesday morning to report a shell was found underneath a blanket.
But at this point, it's still a mystery.
"Well someone must have left it there," the fisherman said. "It's not left over from the war or nothing?"
It could be.
Cobb said the shell could be a World War II-era bomb, suspecting it dates back anywhere from the 1940s to the 1970s.
It was about four feet long and about five inches in diameter.
But police suspect the artillery shell was only dumped in the last few days.
"(The) paint on the outside of the shell was well preserved," Cobb said. "There's not a lot of rust on the ordnance. It doesn't look like it's decayed significantly as if it had been out on the river for 30 or 40 years. It definitely hasn't been on the Columbia for that length of time."