I thought I nearly hit a dolphin a couple of times in Port Stephens but they were just playing with me. My ex hit a Turtle in Port Stephens, sheared the fin right off.
I had a fish beach itself on my board while sailing, I'm sure that if it could talk it would have said WTF, it jumped off pretty quick.
Hit plenty of junk in the water in Sydney, particularly after a big storm. The worst was a running shoe, stopped me dead.
I saw a door jamb in the water the other day! One of the other guys hit a bit of wood with a nail it, left a 40cm gash in the bottom of the board.