This a giant Belemnite from Russia that is called Cylindrotheutis sp. It's the largest that I've ever seen! It comes from near the town of Mikhailov in the Ryazanskaya Oblast region of Russia (south of Moscow). It is Jurassic in age (Callovian stage) but I can't find much more info about them.
For perspective, this first specimen is 6.25" (16cm) long and 1" (2.5cm) wide at the open end.