Question: tmnt how did splinter become a rat?
Answer: Splinter was Hamato Yoshi's pet rat and learned Ninjutsu from him. He witnessed the death of his human master by the hands of Oroku Saki/Shredder in an incident that also sprung him free. ... Splinter was Hamato Yoshi himself, and was mutated into Splinter due to exposure to mutagenic ooze.