A tupilaq is an avenging monster that can be made by someone against an enemy. They were made of natural materials such as hair, bone, plant leaves etc. in secret isolated places and then after suitable chanting was cast into the sea to seek and attack the enemy with an intent to kill them.
As avenging monsters go however there was a degree of egalitarianism involved in that if the enemy was more powerful in a magical way than the aggressor, then he/she could turn the tupilaq back against the maker, so you had to be pretty confident.
Tupilaqs from the museum's collection can be seen in the museum's permanent exhibition One Planet and in the Greenland exhibition.