Cystocarps

Cystocarps are the combined structure of the haploid (1n) female gametophytic tissue, known as the pericarp, that surrounding the carposporophyte (2n), which is made up of carposporangia.

Externally, they can appear like snails sitting on the surface of the plant, like on this red alga, Martensia australis. 

Sometimes they look like hemispherical lumps as in the red alga, Halichrysis coalescens.

Many cystocarps have urceolate ostioles making them look like Greek urns.

You can actually see the spore mass inside the cystocarp in this image of the red alga Dictothamnion saltatum.

In a verticle section of a cystocarp, you can see the dark spores forming a tight ball attached to a fusion cell. This fusion cells is a bit like a human placenta. The surrounding, protective tissue is the pericarp and this tissue is the female gametophyte or ‘mother’. 

Or they can look like golf balls on a ‘T’ as in this red alga, Claudea elegans.