What animals help each other and how?

for example:

the cleaner prawn and the fish. the prawn hang out at one spot when fish come by they open their mouths and the prawns go in the fish's mouth and clean it and then they have food while the fishe's teeth are clean

While harvesting nectar, bees pollinate the plants. The plants grow berries. The birds, bears etc. eat the berries and deposit the seeds in their poop causing more plants grow for the bees to harvest and more berries. The birds help the bees and the bees return the favor.

Not the typical story about the birds and the bees. :-)