As the name suggests, they will bounce towards you. But while they look rather friendly, the Bomb part of its name will tell you otherwise. Upon closing in on your position, they will start blinking and, after a short moment, explode. You can damage them before they explode or activate the blinking and then take cover, but if it hits you, you'll die instantly.
The Summon Stone is very helpful against these enemies, since the ghost will not trigger the explosion but will still be able to damage them.