Unknown egg sac on the seaweed Chondrus crispus

Unknown egg sac on the seaweed Chondrus crispus

Observation - Unknown egg sac on the seaweed Chondrus crispus - UK and Ireland. Description: Single egg sac 2 mm a cross/1/4 mm thick on exposed Chondus crispus (Carrageen) seaweed. South East England. On other pieces of the same seaweed there were other egg sacs laid in rows of up to 7, one behind the other. Great site. Never used before. Hopef

Single egg sac 2 mm a cross/1/4 mm thick on exposed Chondus crispus (Carrageen) seaweed. South East England. On other pieces of the same seaweed there were other egg sacs laid in rows of up to 7, one behind the other.
Great site. Never used before. Hopefully somebody can help id this. Thanks.