Egg sack on Polytrichum

Egg sack on Polytrichum

Observation - Egg sack on Polytrichum - UK and Ireland. Description: group of 6 white squareish egg sacks (possibly spider?) each 4mm across attached to Polytricum leaves in wet heath

group of 6 white squareish egg sacks (possibly spider?) each 4mm across attached to Polytricum leaves in wet heath