Tentacle

A tentacle was a flexible, elongated organ present in some species of animals or alien life forms

The Vendorians were known to have tentacles, as were the Ba'neth. Kelvans in their natural form had hundreds of tentacle-like limbs. (, ,

A symbiotic lifeform which managed to gain access to the starship Enterprise in 2152 snared several crewmembers with tentacles. 

In 2370, Julian Bashir was almost strangled by the tentacle of a metamorphic lifeform, actually a mutated Odo. Bashir injured the creature by cutting its tentacle with a laser scalpel. 

In 2373, the tentacle of a creature grabbed Kira Nerys' hand when a serpent worm was delivered to Deep Space 9.