You are unlikely to be able to tell the different species of hydriods on the rockyshore, without taking them back to a lab with a good microscope, so I have grouped them together. So what even is a hydroid? Well if I said the words ‘jellyfish plant’ I wouldn’t be right.. but maybe not entirely wrong. Hydroids are animals, similar to jellyfish! In fact some jellyfish even have a lifestage where they are a hydroid, so when you find one of these on the shore you could actually be looking at a jellyfish. Hydroids for a plant shaped colony, where each little section is like a minature jellyfish where they use tentacles and some stingers to catch and eat little particles in the water! These are nudibranchs favourite food – because if they eat them they can steal their stingers and become stingy themselves!