Grandma Toad became completely aquatic nearly 300 years ago. Born a tadpole, she developed into her human form around 4 years of age. Throughout her mortal life, she gradually became amphibious with just the slightest hint of that peculiar "Innsmouth look", moving in slow stages to a hybrid creature capable of living completely under the sea. It was the day of her 130th birthday when she finally shed her human body, looking a bit like a squat dolphin once her legs were subsumed. Now, at the age of 432, she has become the graceful creature you see in the picture above. (Image generated by Artbreeder).
Also, this is what she looks like when she's sleeping:
Try not to wake her. She's very grumpy for the first few years after she wakes up.