Sense globe

According to the pamphlet, "Anatomy of the Dalek", sense globes dotted the lower half of the frame of Daleks. (COMIC: City of the Daleks) Other sources sometimes called these parts of a Dalek casing sensor globes. (PROSE: War of the Daleks, Remembrance of the Daleks)

Though these globes were typically arranged in even rows that flared out slightly as they radiating down the body, arrangement was not uniform across all Daleks. The Marine Dalek, for instance, had a different configuration than standard Daleks. (PROSE: War of the Daleks)

Sense globes were evidently the instruments of the Dalek self-destruct process; the Dalek named Metaltron ejected all its sense globes to create a field in which it was completely destroyed. (TV: Dalek)

One Dalek, a recon scout, built itself a new casing in 2019 Yorkshire which had short-range missiles behind each globe. One of these missiles made short work of a tank which sought to destroy the Dalek. (TV: Resolution)

Half a casing's worth of sense globes was among the technology removed from a Dalek by a human guerrilla faction on Earth in the 2010s. (AUDIO: The Dalek Transaction)

Within the Dalek City, tickled a Dalek's sense globes while describing the Doctor's TARDIS as "the dog's unmentionables." (TV: The Magician's Apprentice)

A number of sense globes belonging to the Dalek named Rusty, who was captured by the Combined Galactic Resistance, had been lost or damaged by the time he was found by the Twelfth Doctor aboard the Aristotle. (TV: Into the Dalek) Rusty was still in this battered state when the Doctor met him again on Villengard billions of years into the far future. (TV: Twice Upon a Time)

Behind the scenes
The parodic Comic Relief story The Curse of Fatal Death had its version of the Master outfitted with "Dalek bumps", identified as etheric beam locators, which were placed in such a way that they appeared to give the Master "breasts".

Michelle Gomez confirmed on Twitter that her tickling a nearby Dalek's bumps when referring to the TARDIS as "the dog's unmentionables" was improvised.