Biological
From StarCraft Wiki
Biological units are StarCraft units that consist primarily of non-mechanical components.
Biological units are vulnerable to a wide array of effects, such as a science vessel's Irradiate ability and the queen's Spawn Broodling ability. However, they are immune to effects such as the ghost's Lockdown ability.
They include all zerg units, terran SCVs (also counted as mechanical), marines, firebats, ghosts and medics, and protoss zealots, high templar and dark templar.

