Agreed with bro Iskay , that's likely a peanut worm .
The peanut worm has a proboscis that resembles an elephants trunk, as well as a mouth that boasts an impressive array of tentacles. This bottom burrower feeds on organic materials found in mud and sand, and when done feasting it can turn the proboscis inside out to retract it inside its body. Peanut worms are often tiny but can reach 1.5 feet (0.5 meters) in length.
Taken from nat geo.