Nickelodeons Teenage Mutant Ninja Turtles have discovered a strange creature living in the sewersNis it a friend, a foe, or an uncontrollable monster? Youngsters will dive right in to this action-packed reader. Full color. nNickelodeons Teenage Mutant Ninja Turtles have discovered a strange creature living in the sewers--is it a friend, a foe, or an uncontrollable monster? Boys ages 7-9 will love this action-packed Step into Reading level 4 reader.