What on earth is this?

Hi - Can any wise soul tell me what this is, please?  One foot-square patch of a huge bed looks like Santa shaved off his beard!  I'm used to birds dropping large bones and dead  smaller birds out the sky, I'm used to newts and toads appearing out the blue when there's no water here and I'm used to weird 8-inch long cocoons appearing and disappearing but this is a new one