Blood sausages are a type of sausage that appear in the episode "Spongicus."
They are simply reddish-brown sausages filled with blood. They attract lion fish.
Role in episode
Later on, SpongeBob realizes that the lion fish was chasing the blood sausages wrapped around Patrick's neck, not Patrick himself. After witnessing him eat a sausage on the ground, the lion fish throws the rest of the blood sausages and they land on Plankton.
- Blood sausage on Wikipedia