These are just guesses but they all look like limestone to me.. The top one being just a natural formation or concretion.. Lower left being an impression of a piece of coral and lower right appears to have an impression of some type of plant or coral on it.
Definitely no bone there
Horn coral impression (lower left), a rock w/ interesting quartz band through it, or encircling it- with a weird erosion pattern(lower right), and a concretion. My guess. No expert. Yak