Biological or geological?

[daves64]

This object came with the whale bone I posted about recently. I'm not sure if it's biological or geological so I figured I'd throw it into the room & see what happens. 8.5 cm long x 4.5 cm wide x 8 mm thick (roughly). Flat with a slight curve. This was the shape when found. I sanded the broken part for better internal views. Pics labeled 4, 5 & 6 are closeups. 4 being the break running from side to side, 5 being the break running lengthwise & 6 a closeup of the outside surface. 

[ynot]

Is it hard or soft?

Will it scratch a copper penny or a knife?

[daves64]

I'd say it's a little hard, yeah.. just left a nice groove in a penny. No scratch on a knife blade though.

[PaleoNoel]

It's also a piece of whale bone 

[hndmarshall]

from the looks of it in the really close up pics it has the look of bone

first yours then my plesiosaur or mosasaur  paddle bone and a couple close ups I purchased not sure which it is...

 

what you have could be a worn flat bone of some kind.???

[ynot]

I am thinking more along the lines of a vesicular basalt.

[LordTrilobite]

Piece of worn bone.

[Rockwood]

+1 unidentifiable bone

[Rockwood]

59 minutes ago, ynot said:

I am thinking more along the lines of a vesicular basalt.

Sorry Tony, not home coast advantage on this one. 

[SailingAlongToo]

Photos 1, 2 & 3 definitely look like a chunk of fossilized bone.