Is it a sponge or have some things hatched from it?

Is it a sponge or have some things hatched from it?

Observation - Is it a sponge or have some things hatched from it? - UK and Ireland. Description: Is this some sort of sponge? Or have some things hatched from it. Lots of them washed up on the beach last evening as tide was on its way out. It had been a windy day, we have a lot of those here but I haven't seen as many of these before. Earnse Bay Nor

Is this some sort of sponge? Or have some things hatched from it. Lots of them washed up on the beach last evening as tide was on its way out. It had been a windy day, we have a lot of those here but I haven't seen as many of these before.
Earnse Bay North Walney Cumbria. Please help us to learn more about our local environment.