Sponge?

[D.R. Johnson]

I pulled this off a pebble dashed wall at my grandad's house when I was little. It measures 1x1.5cm . . . Is it a sponge? 

[ynot]

Looks like a piece of a horn coral.

[D.R. Johnson]

4 minutes ago, ynot said:

Looks like a piece of a horn coral.

So it's something like the horn coral you guys identified for me earlier? A rugose coral?

[ynot]

Yes, just cut through at a different angle.

[Rockwood]

2 minutes ago, D.R. Johnson said:

So it's something like the horn coral you guys identified for me earlier? A rugose coral?

It's about what is missing from those.

[D.R. Johnson]

Ok thank you all for your information.

[Herb]

could be a button coral or bryozoa