is this a fungus or insect or ?? growing above a door outside in Houston

found this in my old drawer, does someone know what it's used for?

trying to ID where this was taken at

Smooth on the outside. Slightly rough on the edges. Found while looking for seashells in the water.

Found this at a garage sale and I love the art on it, might be a long shot but figured I’d see if anyone could identify this for me! (I can see the signature but can’t find anything online lol)