Ok… i was messing around with a cube and i got a kind of plate with spikes on it, im sorry if this has been done before but i didnt see it in search.
Start with a basic cube and go into edit mode, select all vertices and press subdivide 3 times and then press ToSphere, make sure it is on 100% and press ok. Now exit Edit Mode and go into Object mode, press Add Modifier and press Subsurf and put it onto level 2. Go back to edit mode and dont deselect the vertices but instead, Move them up so that it looks like a purple ball with lines coming up above it and then a yellow ball at the end of them. Go back to Object Mode and go to top view with 7, no shape both the X and the Y axis to 21 by pressing Skey > Xkey > 21 > Enter and then Skey > Ykey > 21 > Enter, now go into Front View with 1 and then size the Spikes how big u want them
(Varying the amount of subdivide and the level of Subsurf will give different kinds of spikes and different spaces beetween them) BTW i started Blender 2 days ago