A masher is a monster from early editions of Dungeons & Dragons. The masher was mentioned in the 1975 Blackmoor supplement for original Dungeons & Dragons and the 1977 Monster Manual for Advanced Dungeons & Dragons.
The masher is a type of worm-like fish that moves along coral reefs and eats coral. It defends itself with poisoned spines. It is similar to an aquatic purple worm.