One population of the nudibranch Tritonia tetraquetra (a.k.a. Tritonia diomedea) has proven to orient to the geomagnetic field of the earth. We tested the magnetic sense in another population to see if they would behaviorally and neurologically react to rotations of the magnetic field. This was done by observing sea slugs crawling freely surrounded by a 4 square “Merritt coil”. This allowed us to change the direction of the magnetic field inside the cube. We predicted the flipping the magnetic field 180° (so North feels like South) would cause slugs to orient 180° of what was observed under the normal geomagnetic field. We found no significant orientation in the normal field, and no difference in orientation between normal and reversed field over 31 trials in 4 slugs (from a population near Dash Point, WA). Previous results in a population of this species from Bellingham Bay showed a corresponding turn to a 180° rotation of the magnetic field, and our negative results might be explained because we used a different population that lacks this sensory ability. Or if this population does have a magnetic sense, our experimental design differences may account for the lack of observed orientation. In addition to experimenting with turning behavior, we also recorded from specific brain neurons (Pd3) that were previously shown to cause the slug to turn upstream. When flipping the magnetic field, we predicted that both the left and right turning neurons should alter their firing/response rate after flipping the field. Recordings from pedal ganglion flexion neurons show no obvious changes in activity during or after magnetic rotations.