One thing you can do is heat up a sewing pin with a match and very lightly touch the tip to an inconspicuous place on the object. If it's plastic, a small indentation will be left where it melts. If it's clay, then obviously it won't. Of course, this method isn't suggested for an object of value, but if it's plastic it may not have a huge value anyway depending on what it is.
From the pictures I do agree that it looks like a pipe bowl which will be made of clay or other heat resistant material. Although the hole for the stem is rather small for a pipe.
This pin method is a quick way to tell if a piece of scrimshaw is real or not, if you ever come across a questionable piece.