Helicopter pilot reported possibly colliding with a UAS at 300 feet. The helicopter continued its approach and landed at the airport.

Narrative

I was doing a [flight] in south Florida and had a mid air collision with an unknown object. The [flight] was our shortest and has X legs airport to beach; shoreline and then back to airport. While flying offshore flying on the shoreline leg while around 300 ft. I collided with something which at first I thought was a bird but upon later inspection on the ground; I believe it to be a drone. I was unable to see the object since it came from below and was out of my field of view. Upon impact I made sure there were no adverse affects to the aircraft before landing as soon as practical back at the airport of departure. A big factor in this collision was flying low level close to the shore over the water. Drones and helicopters have rights to be in the same airspace under certain conditions and where I was it was legal for them to be there but for me as well. A corrective action for me would be to be mindful that drones could be up to 400 ft. legally and to not fly as low over the shoreline any more.