Thus, a thyroid capable of forming iodotyrosines and iodothyronines is present in all vertebrates. (...) Certain morphologic changes occur after the biochemical evolution of the thyroid has ceased. In the adult lamprey and in most bony fishes, the gland is not encapsulated. (...) In cartilaginous fish, the thyroid is encapsulated. In the higher vertebrate forms, the thyroid is a one- or two-lobed encapsulated structure.[well established][VHOG]

https://github.com/obophenotype/uberon/wiki/Modeling-paired-structures-Design-Pattern

A lobe of thyroid gland that is in the left side of a thyroid gland.

left thyroid lobe

thyroid gland left lobe

lobus sinister (glandula thyroidea)

uberon

UBERON:0001120