Fossil of artifact?

[2goldennuggets]

Found these in the river this weekend. They are about 2" long and 1" tall. Any guesses?

Note the ridge around the base that goes all the way around both these.

 

[BIG61AL]

might be meteorites....see if a magnet is attracted to it.

 

[Treasure_Hunter]

I use to find a lot of them when I hunted creeks, streams and rivers in Missouri. I was told they were neither.