A phenomenon is known when a hermit crab, finding an empty shell with an anemone settled on it, abandons its old house

A phenomenon is known when a hermit crab, finding an empty shell with an anemone settled on it, abandons its old house and takes a shell in an anemone. How does cancer benefit from anemones, and why does anemone settle on the shell of a hermit crab?

This relationship is called mutualism (a kind of symbiosis).
The hermit crab uses anemones for “hunting”. The actinia shoots its stinging cells at the victims, and the cancer eats the prey. Interestingly, over time, the hermit crab develops “immunity” to the venom of anemones.
The sole of the anemone grows on the shell of the crayfish. For her, these relationships are also beneficial: she gets the ability to move around, protection, access to food.