Found this on a beach on the East coast of India - Vishakhapatnam, India
Is this a fossil? A coral?
Its not a fossil.
It is just shells of various marine invertebrates that get stuck together as they grow. It looks like worm-snails on a a large piece of clam shell. the little holes in the clam shell are bored by sea snails and erosion.
there are whole blogs devoted to finding interesting examples. https://natureinfocus.blog/2010/01/13/calcareous-worm-tubes-on-flat-oyster-shells/