Phase Spiderlings are a type of Monstrosity creature in Baldur's Gate 3. Clusters of these creatures are hatched together from three egg clutches scattered throughout the Phase Spider Matriarch arena.
About
Phase Spiderlings are hatched from the small spider eggs found near the Phase Spider Matriarch in the Whispering Depths. The eggs can be destroyed before the spiderlings hatch.
Despite the in-game tooltip only mentioning the 1d4Piercing damage, this attack does an additional 1d4Poison each time as well.
Notes
On Tactician difficulty, they gain +1 bonuses to Strength and Dexterity. Luckily for players, this improvement doesn't significantly affect their combat statistics, as it brings their respective ability scores to odd numbers.