Ceramic raku apples?

Another mystery: I found these strange ceramic apples in a thrift shop for nearly nothing. I first thought they were just ceramics (they are quite heavy) but I don’t understand why there is something on the bottom that looks like sand or some other organic material - have considered mould. Someone suggested there might actually be apples inside the clay, but I’m not sure, they seem too heavy. Two have stalks and two don’t. Has any of you ever seen anything like them before?

There was a Big fashion for nature mimicking pottery in the late 60's and early 70's.. Part of the whole Baby Boomer back to nature movement. So you had pebble vases and such. One wonders if these are part of that. They look very naturalistic and rock like.

I was also thinking Raku, maybe a training exercise for some course even.