Similarity between septal nephridia and Malpighian tubules is that they both leave excretory products in the intestine.

Septal nephridia are excretory organs found in many annelids, such as earthworms. They are located in each segment of the worm's body and are responsible for filtering waste products from the coelomic fluid, a fluid-filled cavity that surrounds the internal organs. The filtered waste products are then transported through the nephridia and expelled through openings called nephridiopores, which are located on the surface of the body segments.

Malpighian tubules, on the other hand, are excretory organs found in insects and some other arthropods. They are located in the digestive system, specifically in the junction between the midgut and hindgut. Malpighian tubules perform a similar function as septal nephridia, filtering waste products from the hemolymph (insect blood) and excreting them into the digestive system. Instead of having nephridiopores, the waste products are transported into the hindgut, where they mix with the feces and are excreted together.

The similarity between septal nephridia and Malpighian tubules is that both excretory organs leave their waste products in the intestine. In the case of septal nephridia, the waste products are expelled through the nephridiopores and deposited on the surface of the body segments. In the case of Malpighian tubules, the waste products are transported into the hindgut and mixed with the feces before being excreted.

This similarity in the excretory mechanism suggests a convergence in the evolutionary adaptations of these two different groups of organisms. Despite their distinct anatomical structures and locations within the body, septal nephridia and Malpighian tubules have evolved a similar method for eliminating waste products by depositing them in the intestine. This may be due to the efficiency and effectiveness of this method in removing waste from the body while also conserving water and other valuable resources.