Club-headed hydroid (Clava multicornis)

Club-headed hydroid (Clava multicornis)

Observation - Club-headed hydroid (Clava multicornis) - UK and Ireland. Description: Spotted just below the sea surface whilst the tide was fairly low. Tentacles did not retract when I

Spotted just below the sea surface whilst the tide was fairly low. Tentacles did not retract when I lifted the Ascophyllum nodosum out of the water. Apologies there is no scale and the photo isn't sharp. Each animal was smaller than 1cm long.
Update: I have been informed that this is a Club-headed hydroid (Clava multicornis)