The sea turtle and remora
Remoras are a group of fish informally known as suckerfish. Lacking a swim bladder, they use a sucking disc on the top of their heads to attach themselves to larger marine animals like turtles.
In this underwater partnership, the remora removes parasites found on the host turtle and cleans epidermal tissue that the turtle sloughs off. In return, the remora benefits by using the host as transport and protection, and feeds on materials dropped by the host.