sharp teeth (radula)
sharp rods 'ribbed' shell
sharp teeth (radula)
sharp rods 'ribbed' shell
tritón
I think Merman is Tritón in Spanish. Even for the Lizard Newt it is Tritón in Spanish. Mermaid it is Sirena in Spanish. Not sure about Merfolk in Spanish.
afilado/agudo - the knife is sharp
listo - for the student is sharp
The boy ribbed the couch.