  Radiolarians are significant contributors to the oceanic primary productivity
and the global silica cycle in the last 500 Myr. Their diversity throughout the
Phanerozoic shows periodic fluctuations. We identify a possible abiotic
candidate for driving these patterns which seems to potentially influence
radiolarian diversity changes during this period at a significance level of
$\sim 2.2 \sigma$. Our finding suggests a significant correlation between the
origination of new radiolaria species and maximum excursions of the Solar
system from the Galactic plane, where the magnetic shielding of cosmic rays is
expected to be weaker. We connect the particularly strong radiolaria blooming
during the Middle Triassic to the so-called Mesozoic dipole-low of the
geomagnetic field, which was in its deepest state when radiolarias were
blooming. According to the scenario, high-energy cosmic rays presumably implied
particular damage to the DNA during the maximum excursions which may trigger
large chromosomal abnormalities leading to the appearance of a large number of
new genera and species during these periods.
