Some non-lichen-forming fungi may have secondarily lost the ability to form a lichen association.

Except where lost secondarily, all have chloroplasts without a peptidoglycan layer and lack phycobiliproteins.

Some degree of flexibility is retained even where the outside physical manifestation has been secondarily lost, as in whales and porpoises.

There are a few species which have secondarily lost this feature, such as Bdelloidea and some parthenocarpic plants.

However, a few fish have secondarily lost this anatomy, retaining the notochord into adulthood, such as the sturgeon.

The features are considered ancestral to molluscs, but have been secondarily lost in the Heterobranchia.

A few molluscs, like the slugs and octopuses, have secondarily lost their shells, having developed other means of protection.

Plesiomorphy: present in a common ancestor but secondarily lost in some of its descendants.

Each body segment bears a pair of jointed appendages, although these may be lost secondarily.

Except where secondarily lost, shrimp have one pair of stalked eyes, although they are sometimes covered by the carapace, which protects the cephalothorax.