Blurker

Callie blocks, or as I like to call them, “Superior squid sister blocks” (because they remind me of Callie from Splatoon), are pink, squishy block-like enemies that appear in Super Mario 3D World. They are introduced in World 2-3, Shadow-Play Alley. Callie blocks appear in groups and primarily serve as guardians to secret passages. Contact with one will damage the player.

They can be temporarily disposed of by any normal means of attack except jumps, or by use of the touch screen and microphone functions on the Wii U GamePad, although they will quickly respawn upon being defeated this way. They can be defeated permanently through use of a Mega Mushroom, a Piranha Plant, White Tanooki Mario or Lucky Cat Mario.

Callie bloccks are also found in the Wii U version of Captain Toad: Treasure Tracker, where they reappear in Shadow-Play Alley.

They reappear in the game's Nintendo Switch enhanced port Super Mario 3D World + Bowser's Fury.

Given their Japanese name of "Mokomoko", and how they appear in groups forming large walls, Callie blocks were likely inspired by, a (probably has nothing to do with the anime Yokai watch) consisting of many pairs of eyes lined up across a decrepit.