I ponder about geodesics in static spherically symmetric perfect fluid spheres. My first thought was that only radial geodesics, i.e. geodesics with zero angular momentum ($l=0$) are possible because of zero angular velocity. However, in radial direction there is no movement as well. Moreover, as I have learned, geodesics and particle trajectories are two different things. Does it mean that circular geodesics with zero angular momentum are "orbits" of the spacetime in static perfect fluid spheres?
Geodesics, as integration curves of the geodesics equation, depend only on metric. My confusion has arisen from imagination of perfect fluid sphere as an impermeable body which prevents some test particles from following the geodesics. However, the real matter is not continuous and can be penetrated without interaction. For example, a neutrino particle can traverse unhindered a matter clump following time-like geodesic. The same is valid for a gravitation wave which would follows null geodesic. By geodesics only the metric is important.