Mr. Eel
From the Super Mario Wiki
A Mr. Eel.
Mr. Eels are eel enemies in Yoshi's Story. They only appears in water levels. They somehow look a bit like Unagi the Eel.
They are not much of a threat. They just mindlessly, swim through the level, somehow going through walls and other things.
Mr. Eels always come in unlimited numbers, which is very useful as Yoshi can simply wait in a safe place and eat the eel to regain life.
