The turtle live is a 20 metres long pond.
{The turtle} is the third person singular, so add an -s at the end of the verb.
Also, you mean {in a pond}?
The turtle lives in a 20 metres long pond.

The turtle’s rear was heard.
{Heard} or {hurt}?
The turtle’s rear was hurt.

Turtle is a kind of exhausting pet.
Ok!

The turtle make me aware how slow they are.
{The turtle} is the third person singular, so add an -s at the end of the verb.
Also, pay attention to the phrase {make sb. aware of sth.}.
The turtle makes me aware of how slow they are.