Star Trek: 8 Easter Eggs From The Lower Decks Season 2 Trailer
2. Kelvan Timeline
Cut to Tendi being surprised by a multi-tentacled, hydra-like alien monster in some kind of facility holding other non-humanoid creatures.
One of the great things about Lower Decks' first season was its expansion of the Star Trek Universe to include a lot more non-humanoid aliens, including ones that previously appeared in Star Trek literature and in Star Trek: The Animated Series.
On Twitter, Ben Robinson (editor of Star Trek Universe: The Official Starships Collection) speculated that this creature is an alien known as a Kelvan. The Kelvans appeared in false humanoid form in the Star Trek: The Original Series episode "By Any Other Name", but were said to have a hundred tentacles in their natural state.